SONGZ User Manual for Overhead Bus AC

SONGZ User’s Manual of Exterior Overhead Air Conditioner
Create healthy human living space
Company Profile
Established in June 2002 with total investment of USD 15.50 million, SHANGHAI SONGZ
AUTOMOBILE AIR CONDITIONING CO., LTD. is a solely foreign-funded enterprise
specialized in the research and development, manufacture and marketing of automobile air-
conditioning system. The company’s headquarter is located in No. 4999, Huanning Road,
Xinzhuang Industrial Zone, Shanghai, covering an area of 110 mu. Now it has more than
2000 employees, among which there are over 300 specialists with middle or high professional
titles. In addition, it holds the shares of Xiamen SONGZ, Anhui SONGZ, Chongqing SONGZ,
Beijing SONGZ, Chengdu SONGZ, and Nanjing Boshilan. It passed ISO/TS 16949:2002
Quality Management System Certification and Automobile Products Certification. In 2007,
it was awarded 'Outstanding Hi-tech Enterprise and Advanced Technical Foreign-funded
Enterprise'. In addition, with complete technical standards system, the company is one of the
key units that are designated to draft the national standards of air-conditioners for passenger
vehicle. Consecutively for many years, it has been crowned 'the Flagship Enterprise of
Air-conditioners for Passenger Vehicle' and 'the Best Manufacturer of Air-conditioners
for Passenger Vehicle' conferred by Urban Vehicle Experts Committee of the Science and
Technology Commission under the Ministry of Construction and BAAV.
In March 2008, SONGZ AUTOMOBILE AIR CONDITIONING CO., LTD was reorganized as
SONGZ AUTOMOBILE AIR CONDITIONING Corporation. Its registered capital amounted
to RMB 180 million controlled by 11 shareholders including Chen Fuquan, BEIJING BASHI
CO., LTD, NANJING ZHONGBEI (GROUP) CO., LTD and SHANGHAI DAZHONG
PUBLIC UTILITIES (GROUP) CO.,LTD, etc. On July 20, 2010, SONGZ was successfully
listed in Shenzhen small and medium-sized market where the stock was abbreviated as SONGZ
SHARE with code number 002454.
Specialized in manufacturing automobile air-conditioner, SONGZ is the largest manufacturer of
air-conditioning system for large and medium-sized passenger vehicles in China. Taking self-
brand operation as the core and being market-oriented, the company independently researches
and develops, designs, and sells a variety of automobile air-conditioner products, which are
widely used in various vehicles including large and medium passenger vehicle, bus, van, light
bus and railcar. The company has filled the blank in air-conditioner production for double-


decker bus in China, and it also manufactured air-conditioners for Beijing Olympic new energy
bus and BRT bus.
In the future, SONGZ will seize the opportunity of fast development in automobile air-
conditioner industry by giving full devotion to its specialization and intensifying investment in
RD, growing into an industry leader who boasts technology, brand and cost advantages and
give satisfaction to enterprise, staff, client and shareholder. In addition, it will make efforts on
the promotion of environmental and energy-efficient products, and assume social responsibility
to become an honored enterprise.
Contents
Notice to users 4
Chapter I Cautions 5
Chapter II Product Description 6
Chapter III Operation and maintenance of air conditioner 7
Chapter IV Operation and maintenance of contained air conditioning unit 17
Chapter V Fast diagnose and treatment of common faults 25
Common Used Circuit Diagram 34


Notice to users
Dear users,
Thank you very much for purchasing our bus air conditioning unit!
For your correct usage, maintenance and troubleshooting of the air conditioner, the Manual
describes in related details as your reference when necessary. The information included in the
Manual is applicable to the driver and mechanic who operate SONGZ bus air-conditioner.
Please hand over the Manual to the driver.
The Manual is used in conjunction with Product Quality Warranty Manual.
Please keep the Manual in vehicle for easy reference.
The Manual is for your reference only and subject to change without notice.
Please feel free to point out the inadequacy in the Manual if any.
Your opinions and suggestions on further improvement of the product
would be appreciated.
SONGZ reserves the right to modify the Manual from time to time without notice.
The Manual shall not be copied or printed in any form without SONGZ’s approval.
Chapter I Cautions
1.1 Safety Issues
1. Promptly switch off the air conditioner if fault alarm occurs.
2. Don’t touch the driving parts (fan, belt, belt pulley, etc) and high-temperature parts
(compressor and high pressure pipeline) of the system during operation or after shutdown of
the air conditioner.
3. The electrical part of the air conditioner shall work in dry.
4. To avoid accidents, the air conditioner shall only be dismounted by maintenance worker.
5. Following operations are not allowed.
a. Directly inflate the air conditioning system with nitrogen for pressurized leak detection
without installation of reducing valve.
b. Replace nitrogen with oxygen for pressurized leak detection.
c. Use refrigerant instead of vacuumizing device to evacuate the air inside the system.
d. Directly take oxygen weld when the system is yet complete decompressed.
e. Let the vehicle operation unchecked after the air conditioning system is pressurized and
during maintenance.
f. Fill R134a air conditioning system with other models of refrigerants such as R12, R407C,
R22.
g. Fill refrigerant oil that is not intended for the compressor of the system.
1.2 Suggestions on Operating Environment
1. Park the air conditioned bus in a shady and well-ventilated environment when stop.
2. During operation of air conditioner, please close the doors, windows and ventilation
equipment of the bus.
1.3 Rules on Customer Service
1. If any maintenance service is needed, please contact SONGZ customer service department,
service centers or service stations and show the Product Quality Warranty Manual.
2. We are not liable for any problems arising due to incorrect installation and improper use of
SONGZ products.


Chapter II Product Description
Typical overhead air-conditioner picture
(Figure 2-1)
Condenser
Evaporator
(Figure 2-2)
Chapter III Operation and
maintenance of air conditioner
3.1 Function of LED Numerical Control Manipulator
LED manipulator (Figure 3-1)
1. Power Switch
After the power switch of the vehicle is on, press to start up the air conditioner and press
again to shut down.
2. Operating Mode
Press MODE to select the operating mode of the air conditioner, i.e. refrigeration,
ventilation and heating.
When goes on, the air conditioner is “refrigerating” and “ventilating”.
When goes on, the air conditioner is “ventilating”.
When goes on, the air conditioner is “heating” (invalid for the product without heating
function).
When AUTO goes on, both the refrigerating condition of the air conditioner and the
lowest temperature to be reached in vehicle are automatically controlled by manipulator
based on the temperature inside the vehicle.
3. Fresh air
Press Fresh Air to select start-up or shutdown the fresh air device and ozone
generator. During operation, the corresponding green indicating light is on.
2.1 General
(1) The ultra-thin streamline design ensures an elegant appearance of the whole vehicle.
(2) Good component matching inside the product ensures high refrigerating efficiency of
the system.
(3) The selection of rational fresh air mechanism ensures a comfortable environment for the
clients (providing 10~20% fresh air).
(4) The product only uses green and environment-friendly refrigerant – HFC134a in hope of
a minimized environmental pollution.
(5) The product mainly consists of exterior overhead evaporator and condenser assembly,
compressor assembly, pipeline and manipulator, evaporator and condenser are installed
at top.
2.2 General Layout


When goes on, fresh air device starts to work with the vent opened for long term.
When O3 goes on, ozone generator starts to work.
When AUTO goes on, fresh air supply is in auto-operation mode.
Note: the function is invalid for the air conditioner without functions of fresh air supply and
sterilization.
4. is a red nixie tube displays the temperature inside vehicle, defrosting temperature
and fault code.
5. Air volume control and air speed indication:
is an air speed control key to switch the fan in circulation from low speed to medium
speed to high speed.
Light beam: fan speed is showed by the illuminated LED on light beam.
3.2 How to Switch-on The Air Conditioner on LED Nnumerical Control
Manipulator
When the engine is started up, press the power button to activate evaporator fan. Since
manipulator has power-off memory function, the air condition simultaneously turns into the
running status that exists before shutdown, whereupon it is recommended to adjust the running
mode of the air conditioner and set its running parameter if required.
1. Press MODE to select running mode of the air conditioner, for example, when select
Refrigeration, the light shows green, and the air conditioner starts to refrigerate. The idle
speed boost will start to work as well if it is equipped in the engine.
2. Press or (hold on for more than 2s) to scroll the Defrosting 1 temperature – Defrosting
2 temperature - Setting temperature. When red nixie tube displays setting temperature, the
temperature to be reached inside vehicle can be set within 16°C~32°C. Press or once
to increase or decrease the setting value by 1°C, otherwise, if neither or is pressed
within 5s, it will automatically switch to the temperature inside vehicle display mode.
Note: Since human body’s comfortable temperature is 22°C~28°C, it is suggested to set
the temperature within this range. Once the temperature inside the vehicle is lower than the
setting value, sensor will promptly transmit the induction signal to manipulator whereby the
air conditioner will stop refrigerating.
3. Press to adjust the required air speed.
4. If you feel the air inside vehicle is turbid, press to drive the fresh air motor open the vent
in which fresh air flows into the vehicle. When shows green, the vent opens for long
time.
If AUTO shows green, fresh vent will open for 3 minutes and close for 27 minutes, and then
goes in this cycle.
If O3 shows green, the ozone generator is at work.
5. If you want to switch out refrigerating mode to auto-running mode, press MODE till AUTO
shows green, and then the refrigerating system will conduct auto-control based on actual in-
vehicle temeprature (During auto-operation, don’t press the key on manipulator, otherwise it
will exit the auto-mode.). The temperature set below AUTO mode is a conventional value.
(1) In AUTO mode, if the temperature inside vehicle is higher than 25°C and the temperature
outside vehicle exceeds 23°C, the air conditioner will turns into refrigerating status
where the conventional setting temperature is 25°C, i.e. Tset=25°C.
(2) In AUTO mode, if the temperature inside vehicle is within 21°C-24°C, the system will
operate in low-speed ventilating status.
Air speed indicating light (Figure 3-2)
Low speed Medium speed High speed
6. Browse buttons:
: increase temperature or page up the information;
: decrease temperature or page down the information.
7. Fault alarm indication:
: indicates air conditioner fault alarm if red LED flashes.
Note: MODE, Air Speed, Fresh Air and temperature setting buttons all
have power-off memory function!
Power-off memory function means that manipulator’s running mode, fresh air
working condition, in-vehicle setting temperature and air speed keep the same
as those before last shutdown.
After the fan starts up for 30 seconds and then the compressor will be
activated!

10
Create healthy human living space 11
(3) In AUTO mode, if the temperature inside vehicle is lower than 20°C, the air conditioner
will turn into heating status where the conventional setting temperature is 20°C, i.e.
Tset=20°C.
6. Check the temperature inside vehicle
The temperature inside vehicle is displayed in default mode. When is switched on, the
nixie tube displays the temperature inside vehicle, which will change with the variation of
refrigerating time and thermal load of carriage.
The display of the temperature inside vehicle ranges from 0.0°C to 60.0°C (with accuracy
down to 0.5°C); ‘ Lo ’is displayed when the temperature inside vehicle is lower than 0.0°C,
and ‘ Hi ’is displayed the temperature inside vehiclee is higher than 60.0°C.
7. Check defrosting temperature
Press or and hold on for more than 2s to scroll Defrosting 1 temperature – Defrosting
2 temperature.
The display of defrosting temperature ranges from 0.0°C to 90.0°C (with accuracy down
to 0.5°C); ‘ Lo ’is displayed when defrosting temperature is lower than 0.0°C, and ‘ Hi ’is
displayed when defrosting temperature is higher than 90.0°C.
8. Check fault code
For some faults, we can analyze and determine their causes based on the display, receiving
and feedback commands on numerical control manipulator.
When fault indicating light goes on and the temperature inside vehicle is displayed, press
and the digital window will display fault codes in order of EP1, E 1, E 2, EU1; press
, the digital window will display fault codes in order of EU1, E 2, E 1, EP1; if related
alarm code is defaulted when scrolling, the displayed codes will move forward in order. See
Table 1.
Table 1 Air Conditioner Fault Codes Comparison
Fault Code Meaning of Fault Code Potential Cause
Fault code EP1 is displayed,
indicating unusual pressure–
electrical or system fault
Refrigerant leakage (low pressure
protection)
Fan of condenser malfunction (high
pressure protection)
System, dryer or expansion valve
blockage (low pressure protection)
Pressure switch failure ( protection on
high pressure switch or low pressure
switch)
Fault code E 1 is displayed,
indicating that temperature
sensor is cut off.
Sensor is damaged
Sensor connection is loose
Fault code E 2 is displayed,
indicating the temperature
sensor of evaporator is cut
off (i.e. defrosting sensor is
disconnected)
Sensor is damaged
Sensor connection is loose
Fault code EU1 is displayed,
indicating voltage is too low (the
tested input supply voltage of
manipulator is less than 20V for
consecutive 13 seconds)
Generator speed is too slow
Belt is loose
Regulator fails
Generator stator winding or field
winding fails
Supplementary (notes!):
When (supply) voltage is higher than 32V for consecutive 13 seconds, power supply will
automatically cut off with ventilation, refrigeration and fresh air supply stopped working
while excitation will maintain effective and panel display will keep on.
When (supply) voltage is higher than 45V, power supply will automatically cut off with
ventilation, refrigeration and fresh air supply stopped working while excitation will
maintain effective, but panel display will keep off.

12
3.3 Cautions for Use of the Air Conditioner
1. Please keep the manipulator of air conditioner away
from water
Manipulator, an electrical subassembly, may lead to the malfunction of air conditioner if water
flows into it. Please pay special attention to:
After parking the bus, please close the doors and windows on right and left sides of the
cab to prevent rain soaking and damaging the manipulator.
When vehicle is under cleaning, please close the doors and windows on right and left
sides of the cab to prevent water inflow and damage to the manipulator.
In process of driving, driver’s teacup should be placed away from the manipulator to
avoid tea water splashing into the manipulator, causing in damage.
2. Air conditioner can only be switched on if engine is started up
If air conditioner is switched on before start of engine, clutch will pull in with the driving
disc of compressor, and the later start of engine will cause much friction between clutch
chuck and driving disc of the air conditioner because the instantaneous torque of engine
reaches to the peak. Such operation lasting for a long term will result in early wear-down
of the clutch. (With regard to the sudden shutdown due to the temperature inside vehicle
reaching set value, the instantaneous wear-down of chuck is normal.)
3. Don’t use the air conditioner when fault light or under-voltage light goes on.
4. In seasons when it is suitable to use air conditioner, engine’s idle speed can be appropriately
turned up and kept within 650~850rpm/min. In general, engine is equipped with special idle
speed boost for air conditioner. If it is found that the revolving speed of engine fails to greatly
increase after air conditioner starts refrigerating, it is necessary to check idle speed boost or
ECU for normal operation or notify the manufacturer of engine or passenger vehicle.
5. In out-of-service seasons, it is forbidden to remove the compressor and generator
transmission belts of air conditioner.
6. During operation of air conditioner, please close all the doors, windows and the air
interchangers (except fresh air device).
7. Do not close all air outlets of air conditioner and keep at least 1/3 outlets opened.
8. Generally, do not short-circuit the thermal control or defrosting protection (i.e. No forced
refrigeration).
9. Under no circumstance should the high/low pressure switch be short-circuited.
Correct usage ensures the best refrigerating effect of the air conditioner
with minimum faults and high reliability.
3.3 Maintenance of Air Conditioner
1. Avoid exposing the air conditioned vehicle in sunshine when parking in summer.
Exposure to sunlight will cause rapid increase of thermal load of the vehicle, which will
reduce refrigerating effect and cooling rate during the operation of air conditioner.
2. Check out the intensity of the belt and adjust it if necessary (see the Figure)
The intensity and wear rate of belt should be checked after 48-hour running of new vehicle
or every month. At present, in China it is common to control belt tension via hand-feel, i.e.
vertically pressing 10kg (about 98Newton) force onto the belt at center position between two
belt pulleys with deflection (offset) shown as follows:
(Figure 3 -4)
deflection per meter of
center distance
center distance
e
x
t
e
r
n
a
l
f
o
r
c
e
10mm
Check the belt for wear rate and promptly replace the unqualified belt. (Note: two belts
should be the same during displacement.)
3. Check out the cleanness of filter screens of both return air grille and evaporator and regularly
clean the filter screens (there are three filter screens at each return air grille)
Generally, it is necessary to clean the city bus once or twice a week, and clean coach once
a week. In dusty area, the interval of cleaning can be shortened as appropriate.
Filter Screen at least cleaned once a month in out-of-service seasons
(Figurer 3-3)
Manipulator is installed on the left side of cab

14
Following cleaning methods are suggested:
Clean the surface of condenser and evaporator cores by high pressure water gun with
cleanser essence.
Blow the surface of condenser and evaporator cores with high pressure air gun.
Note: the high pressure water gun or air gun can be used only after being adjusted
to proper pressure, and the fins should not be beaten down; for specially dirty cores,
especially evaporator core with filter screen not being cleaned for so long that lots of
dust and dirt covered on fins, it is necessary to wash it with special fin leaner diluted with
water for air conditioner
7. Frequently check the compressor for any oil leakage or oil shortage:
Generally, coach air conditioner adopts piston compressor, of which the shaft is sealed via
the sliding seal surface of shaft seal, and the sealing property and lubrication of the shaft
seal all depend on refrigeration oil, so a little oil leakage (dropping) is normal. During actual
application, driver should examine the compressor as necessary, and promptly repair it once
oil leakage arises due to abnormal shaft seal.
Examining methods:
(1) The run-in period of compressor is 250 hours. The oil leakage during this period is normal,
and oiling is necessary only when a great deal of oil leakage occurs.
(2) The refrigerant level of compressor can be observed via sight glass: check the refrigerant
level 10-15 minutes after startup. Since the actual installation position of compressor is
different (oblique position), it’s better to examine the refrigerant level through two sight
glasses, at least through one sight glass. (Part of refrigerant flows into overhead section
during operation, and it should be verified repeatedly when debugging new vehicle).
It is every driver’s responsibility to regularly clean the filler screen of air
conditioner and keep a clean inside environment of the bus.
5. Check the amount of refrigerant and the dryer condition:
The dual cores should be cleaned at least once a year. The reversed fins found during
cleaning should be corrected with fin comb.
(Figure 3 -7)
Low of refrigerant inside Level Glass
(Figure 3 -6)
Level glass Dryer
(1) Check the moisture content of system via level glass of return air grille. If the color of
test paper goes green, it means the moisture content is normal. If the color of test paper
gradually becomes yellow, it means the moisture content is high and dryer fails where it
is necessary to replace the dryer.
(2) It is possible to judge if the refrigerant is enough by observing the movement of
refrigerant through level glass can help (See Figure 3-6).
No obvious but occasional bubbles in liquid flow means refrigerant is enough, in contrast,
obvious and constant bubbles in liquid flow means refrigerant is not enough.
6. Check the heat exchange fins of evaporator and condenser cores for their cleanness:
Regularly cleaning heat exchanger (of evaporator, condenser) of the air conditioner ensures
the best refrigerating performance of air conditioner and avoids any faults of air conditioner
arising due to excessive dirt on the surface of heat exchanger.
Evaporator
core
Condenser
core
Figure 3 - 8
Detach the return air grille and clean the filler screen
Warning! If the filter screen is not cleaned regularly, the
heat exchange efficiency of evaporator may be seriously
impact for the case in which lots of dust and greasy
dirt enter into evaporator core, resulting in significant
decrease of refrigerating effect, and even causing
filter screen blockage, less air volume, or incomplete
evaporated fluid refrigerant entering into compressor to
give rise to “liquid hammer” of the compressor.
(Figure 3 -5)

16
(3) When the air conditioner is not
running, it is suggested that the
oil level of one compressor be not
lower than 1/3 of the sight glass.
8. Inject lubricating grease for belt
pulley bearing and support shaft
sleeve of the air conditioner once
a year to ensure lubrication of the
bearing. (2#lithium base grease is
suggested):
9. Regularly turn on the air conditioner
in winter:
Regularly turn on the air conditioner in winter to ensure its operation twice a month (running
for 5-10 minutes each time), so as to guarantee the lubrication of mechanism inside the
compressor.
Before start of vehicle, lock the clutch chuck of rotating compressor with hand or monkey
wrench to make the chuck of compress change from being heavy to being light (advisable),
then switch on the air conditioner for about 5 seconds, and switch it off. After this, switch
on the air conditioner once again for about 5-10s and switch it off as before. After above
procedure, the air conditioner can be normally started up.
For the users in north, the abovementioned operation procedure should be followed before
the first startup of air conditioner in spring.
10. Check the pipeline and joint
Frequently check the exposed rigid tube, flexible pipe and pipeline joint in case of any
interference, wear, extrusion and looseness. The broken pipeline and loose joint will cause
refrigerant leakage, resulting in decrease of refrigerating effect of the air conditioner and
even no refrigeration of the air conditioning system. The extruded pipeline will form stop-
flow of refrigerant, which will impact refrigerating effect of the air conditioner.
11. Check the wiring cluster
Frequently check the exposed wiring cluster and its connector assemblies in case of any
interference, wear and looseness.
Chapter IV Operation and maintenance of
contained air conditioning unit
4.1 Description of manipulator II’s Functions
Manipulator II (Figure 4-1)
1. Key switch
Key switch is set to start and stop the engine of power unit, and control the operation and
shutdown of air conditioning system specialized generator.
2. Power indicating light
The power indicating light is set for power indication of power unit. When key switch is at
“On”, the power indicating light illuminates to power on, and at “off”, the power indicating
light extinguishes to power off.
3. Oil pressure alarm indicating light (see Figure 4-2)
Oil pressure alarm indicating light is set to warn the condition in which the lubricating oil
pressure of engine is too low, controlled by the switch-on/off
of oil-pressure in forced lubrication pipeline of engine. If the
alarm indicating light goes on, turn the key switch to “Off” to
promptly stop engine’s operation, avoiding damage of engine,
and check machine oil level of the engine.
Note: During pre-startup of engine phrase, when key
switch is at “On”, the oil pressure indicating light
showing on is normal, and it will show off about 10s
after start up of engine.
4. Water temperature alarm indicating light (see Figure 4-3)
Water temperature alarm indicating light is set to warn the the condition in which water
(Figure 4 -2)
Sight glass
(Figure 3-9)

18
temperature is too high, controlled by the switch-on/off of cooling water temperature switch
inside engine water cooling pump. If the alarm indicating light goes on, the engine will
automatically shutdown to avoid engine overheating.
When water temperature alarm indicating light
goes on, check if the level of engine water tank is
too low, air inlet passage is clear or the belt of water
pump is tensioned.
Note: When normal operation of engine or
after water temperature alarm indicating light
illuminates, please do not open the engine water
tank lid, to prevent operator being injured by the
cooling liquid.
5. See “Function description of manipulator I” in Chapter IV for other information about
manipulator.
4.2 How to switch on the air conditioner:
1. Startup of engine
(1) Before startup of engine, make sure the air conditioner is powered off and turn the key
switch clockwise to “Warm up” position (For the engine with different configuration, the
warm-up function probably doesn’t work, so the position can be skipped over) to prepare
the startup of engine. Warm-up time should not be more than 12s each time. (see Figure
4-4).
Note: If the engine fails to start while starting motor
has been running for 30 seconds, please re-start
the engine after one minute. If the engine fails to
start for three consecutive times, please check the
oil line, air line and electrical system, remove all
related faults if any, and re-start the engine.
(3) Turn key switch clockwise to “Start” position and
the engine will be started by the driving of starting
motor. (See Figure 4-6).
(4) When engine is started up, release the key switch,
which will automatically rebound to “On” position.
The engine operates at low speed to make preparation for switch-on of air conditioner.
Note: When passenger vehicle air conditioner is running, key switch
should keep at “On”.
2. Switch on the air conditioner (see How to switch on the air conditioner by manipulator I)
3. Introduction to timer function of manipulator
The manipulator has timer function, that is, the accumulative service time of the air
conditioner can be displayed and viewed through simple operation. If the manipulator is
changed in the midway, record the service time at the time of changing the manipulator. If it
is necessary to inquire the accumulative service time later, what we have to do is only to sum
the recorded service time and the current displayed service time.
Operation method: hold on both and for 5s, nixie tube will display the first 3
digits of service time of the system; within 10s, press to display the last 3 digits of
service time of the system, then press again to display the first 3 digits of service time
of the system; within 10s, there is no or pressed, it will automatically return to
in-vehicle temperature display.
The format of accumulative service time of air conditioner is in form of XXX, XXX. The
unit of first 5 digits is 1-hour, and the unit of last digit is 6-minute, with total statistic of 100
or 1000 hours.
4.3 Cautions for usage of air conditioner
1. See “Cautions for use of air conditioner” in Chapter III for other operations except engine.
2.The adjustment and maintenance are subject to the instruction for usage and related
regulations.
(1) Make sure the storage battery is fully charged, and check the terminals for cleanness and
(Figure 4-3)
(Figure 4 – 4) (Figure 4 – 5)
(2) Turn key switch to “On” position, then the “Power” and “Oil pressure” indicating lights
will illuminate. (see Figure 4-5)
(Figure 4-6)

20
check the connection for reliability.
(2) Prior to use of new engine, running-in according to regulations is necessary (see the Table
below), and the engine should not be suddenly accelerated.
(3) Please use the refrigerant that is prepared based on specified ratio and mixed with
antifreeze.
(4) The engine without supercharger should use CC class machine oil, while the engine with
supercharger should use CD class or above machine oil.
(5) The engine with supercharger should idle for 3-5 minutes after startup, and also idle for 3-5
minutes before stop.
(6) Machine oil pressure should be higher than 392KPa when it keeps at normal water
temperature (80~90°C) and medium vehicle speed, the normal
(7) The fuel of engine is 0# diesel (10# diesel is preferred in north in winter).
(8) During engine running, it is necessary to promptly shutdown and check malfunction if
any.
(9) Open the radiator cover at first before discharging the water in cooling system (don’
t open until water temperature decreases, otherwise the hot water that spouts out would
cause injury), then open the discharging plug screws at left bottom of radiator and left
side of cylinder.
Specification on running-in of new engine
(4) Re-fill machine oil and clean or replace filter element after vehicle travelling reaches to
1000 and 3000km.
4.3 Maintenance of Air Conditioner
1. Check Engine Machine Oil of Power Unit
Verify the oil level is between the highest and lowest scales of oil dipstick. (see Figure 4-7)
Cautions for running-in of new engine:
(1) Check the volume of machine oil, water and diesel and make sure the battery is charged,
and eliminate any leakage.
(2) Use torque wrench to turn engine crankshaft several rounds before starting engine.
(3) After engine is installed in vehicle, running-in should be done on Class 1 or Class 2 road.
No running-in is done on any poor road, especially on sands.
(Figure 4-7)
2. Check Cooling Open water tank lid to check the volume of cooling water. The rated volume
of cooling water is 9 liter (full).
(Figure 4-8)
3. Check the Air Filter of Engine
(1) Remove air filter element from the filter. (see Figure 4-9)
Mileage (Km) Load Vehicle speed
0 ~ 200 No load Less than 50% of the rated speed of the engine
200 ~ 800 Less than 50% of the rated load Less than 50% of the rated speed of the engine
800 ~ 1500 Less than 75% of the rated load Less than 75% of the rated speed of the engine
1500 ~ 2500 Full load Lower than the rated maximum speed

22
(2) Repeatedly blow with the compressed air.
(3) The replacement period of air filter should be based on the requirement specified in
instruction for use of engine.
(Figure 4-9)
Item
Maintenance
interval
Status Contents and requirements
Air outlet Every day
Before and after
startup
When air conditioner is running, it is necessary to keep 2/3 air
outlets opened to guarantee good circulation of airflow; Check if
the volume of air out at two sides is similar.
Filter screen of
return air grille
Every week Before startup
Wash the filter screen (sponge block) of return air grille with
water, and the washing can be earlier if vehicle runs in dusty area.
Filter screen of
evaporator core
Every month Before startup
Wash the filter screen of evaporator core with water, and the
washing can be earlier if vehicle operates in dusty area.
Condensate pipe Every day After startup
After air conditioner has operated for 1 hour, check the
condensate pipe for any discharge of condensate water. In South
or coastal area with high humidity or in rainy season, there is
large amount of water discharge.
Transmission belt
Every week Before startup
Check the belt for its intensity and wear, and adjust or replace it
if necessary. Vertically apply 10kg force (about 98 Newton) with
thumb to the belt between two belt pulley, its deflection should be
as follows: the deflection of center distance per meter is 10mm.
Compressor oil
level
Every day or
every week
Before and after
startup
Check the compressor for its oil level. The refrigerating machine
oil level of compressor can be observed through sight glass: over
4∕5 30minutes after stop of the air conditioner, and 1∕4~3∕4 in
working condition. If the level is lower than above criteria during
250-hour running-in period, it is necessary to replace felt and
add refrigeration oil; if the level is lower than above criteria after
running-in time, the shaft seal should be replaced.
Electromagnetic
clutch
Every day
Before and after
startup
Prior to power-on, check the clutch bearing for any abnormal
sound; after power-on, check if the electromagnetic clutch can
promptly pull in /separate, and slip.
Compressor
Every year Before startup Check the bolt of fixed support of compressor for any looseness.
Every week After startup
During non-use of compressor, check different components for
normality by operating it once every week, several minutes each
time
Fan Every year After startup Check if there is any abnormal sound during operation.
Dryer Every year After startup
Replace the dryer (note: if the test paper of sight glass fails to
become yellow, and refrigeration of the system is normal and
the sight glass is clear and transparent, the dryer may not be
replaced).
Socket connector,
terminal
Check if the cable of compressor clutch and the terminals of
generator are loose.
Fuse Every month Before startup
Check if the master fuse of 150A power supply, the fuse of 50A
fan, and the 5A, 7.5A, 10A inserting type fuses are intact, and if
the retaining screw at both sides and base are loose.
Transition wheel Half a year Before startup Refill lubricating grease (may inject it from “grease fitting”.)
Support shaft
sleeve
Half a year Before startup
Refill lubricating grease (may inject it from “grease fitting”.)
Refill lubricating grease (may inject it from “grease fitting”
Instruction Table for Driver’s Routine Operation and Maintenance
See SONGZ User’s Manual of Passenger Vehicle Air Conditioner for the rules on operation and maintenance by
professional technician (Version No.: JS-2010-01 by Zhong Huawei).
If any fault occurs, please inmmediately contact SONGZ service center or service station.

24
Instruction table for routine operation and maintenance of JMC engine
Item Daily
1000
km
3000
km
6000
km
18000
km
36000
km
Contents
Dashboard,
manipulator
● Check if dashboard/manipulator pointers and display functions are normal.
Pipeline, connector,
seal
●
Check if there is oil leak, water leak, air leak and electric leak at connectors
and seals.
Belt ● Check the transmission belt for its intensity and wear.
Bearing (with
lubricating nipple)
Check and promptly fill lubricating grease into belt pulley bearing.
Water tank ● Check if the cooling water is enough.
Air filter
● Check the air filter and blow it with compressed air to make it clean.
● Wash air filter
● Replace filter element (air filter element of paper filter element
Air valve ● ● ● Check and adjust the gap of valve inside
Air inlet/exhaust
system
● Remove the scale deposit inside the system
Crankcase ventilation
system
● Remove the scale deposit inside the system
Air inlet/exhaust
manifold
●
Check if nuts are loose. The torsion should be evenly distributed when
fastening the nuts of air inlet/exhaust manifold, otherwise air leak would
occur.
●
Check if the air inlet/exhaust manifold has any crack and void, and if the
gasket is damaged or washed out.
● Check the oil pan for any oil leak (when engine running)
Machine oil filter
● Wash machine oil filter
● ●
Replace the machine oil filter element (also may advance or delay the
maintenance as appropriate).
Replace the machine oil filter element
Machine oil pool
● Check if the oil amount of machine oil pool is enough.
Replace machine oil
● Replace the machine oil in oil pan
Oil tank and oil tube ● Wash oil tank and its pipeline
Diesel filter
● Wash or replace the paper element of oil filter
● Wash fuel filter
●
Replace diesel filter element (also may advance or delay the maintenance as
appropriate).
Oil pump
●
Check the oil line for its tightness, and observe if there is any local
overheating and abnormal sound.
● Wash the interior filter screen of fuel inlet neck of transfer pump
●
Check the oil nozzle for its oil level and oil injection pressure, the normal
pressure is 18.1MPa(185kgf/cm2).
●
Check the fuel injection pump for its oil supply angular advance (16°crank
angle in front of top dead center for JX493Q1, and 14°crank angle in front of
top dead center for JX493ZQ), oil supply and the uniformity of oil supply of
cylinders, and make adjustment if necessary.
Lubrication clutch
release bearing
● Refill lubricating grease
Storage battery ● Check the storage battery for any crack and electric leak.
Generator ● Check the generator for its fastening
● Check the generator for its normal operation
Starter ● Remove and wash the starter
Various electrical
connectors
●
Check or tighten the socket connectors, relays, fuses, and terminals to ensure
good connection.
The items involved in each phase of maintenance include all the items involved last phase of maintenance.
Chapter V Fast diagnose and treatment of
common faults
The Chapter abstracts following typical fault cases of SONGZ air conditioner for passenger
vehicle for reference in order to help the driver rapidly treat the general faults arising and
accurately report the failure by calling the technician.
1. No refrigeration:
This is a common fault of refrigerating air conditioner, which is caused due to many factors.
First, it is necessary to check if the setting temperature of manipulator is correct. In case of the
temperature inside vehicle lower than the setting temperature, we can lower the temperature
inside vehicle, but the setting value should be within 16°C~32°C. In summer and autumn when
there is big difference of temperature between morning/afternoon and noon, the temperature
inside vehicle is probably less than 16°C where the air conditioner will not work. In this
case, driver should not switch on refrigerating function until air temperature rises again. If it
feels stuffy in vehicle, please turn on the “Ventilation” function of air conditioner or open the
ventilator (skylight) on the vehicle.
Other factors:
No refrigeration due to loose belt: in such case, we would hear the belt slip in engine chamber
when air conditioner is switched on, then refrigeration indicating light shows off at once, the
engine speed significantly decreases at the same time and engine stops running. We can analyze
and know the reason based on the principle of air conditioner: compressor, as the heart of
refrigerating system is driven by engine, with power transmitted by belt. If the belt is loose, it
will cause belt slip, and generator fails to keep synchronous operation with engine, resulting
in sudden decrease of engine speed that directly leads to too low current transferred to clutch
coil. Since the current is excessively low, the pull-in between clutch chuck and driving disc is
insufficient, and friction and slipping arise, resulting in compressor’s failure in running and no
refrigeration of air conditioner. On this occasion, what should be done is only to appropriately
adjust the belt.
No refrigeration due to fuse burnout of compressor (clutch coil): first, check if the inserting
type fuse in control box is burnt out. After replacing the fuse, make sure the fuse is firmly
JMC maintenance items are subject to User’s Manual of JMC Engine, and the maintenance of Fukuda Aoling 4JB1
series of engines is subject to Fukuda User’s Manual. During maintenance, if any fault occurs, please immediately
contact SONGZ service center or service station.

26
secured, and check if the socket connectors of manipulator and compressor coil are properly
connected, because poor connection will cause high current, resulting in fuse heating and
burnout.
No refrigeration due to the loose socket connector of engine clutch coil: it is generally
caused by excessively tightened wiring harness or poor connection of socket connector. Please
re-insert the socket connector and secure firmly the two ends of wiring harness.
No refrigeration due to refrigerant leak: in this case, the “fault light” of manipulator flashes
red. At this moment, the “Refrigeration” should be switched off promptly. Check the engine
chamber, flexible pipe and copper pipe inside air passage for any leakage. In case of slight
leakage, there is refrigerant stain at connector or weld; in case of fast leakage, we can hear the
sound of leakage. Report the check results to SONGZ service center, where the professional
technician will treat the problem.
2. Poor refrigerating effect of air conditioner
Closing most of air outlets will cause poor
refrigerating effect and less air volume. Sine
the temperature of front part of the vehicle is
higher than that of rear part due to direct solar
radiation, sometimes the driver would adjust
the temperature inside vehicle according to own
feeling, resulting in some passengers feeling “too
cold” and closing the air outlets. However, the
more air outlets closed, the less air supplied. If
the defrosting sensor fails, it will even cause evaporator core icing, lead to “short circuit” of
in-vehicle return air inlet and circulating air flow, resulting in “fault” of poor refrigerating
effect of the air conditioner. To solute such problems, please set the temperature inside
vehicle at the value for passengers’ comfort, and open all air outlets.
Poor refrigerating effect due to bad carriage seal. The solution is: close all doors and
windows.
Poor refrigerating effect due to shortage of refrigerant. In order to determine this case,
the first is to check via sight glass if the refrigerant is enough (see Item 5 of 3.3 for
related standard), and notify SONGZ service center to solve the problem.
3. Less air volume or no air supply from the air conditioner
The connection of generator is loose
or broken, causing no air supply
of air conditioner. In this case, it is
necessary to check the connection
of output, grounding and excitation
of generator terminals in the air
conditioner. To solute such problems,
please re-connect or crimp the
terminals.
No air supply is caused by fuse
burnout, generally due to the damaged fuse of main power source 150A or evaporator fan. In
general, 150A main power supply is equipped with spare fuse that can be used to solve the
problem on spot. If the fuse of fan is damaged, the problem can only be solved by SONGZ
service station.
The broken speed regulation resistance of evaporator causes less air volume on both sides or
on one side. On this occasion, please contact the SONGZ service station.
4. Less air volume and significant decrease of refrigerating effect
If it happens during normal running of air conditioning system, it is often due to extremely
dirty filter screen of air conditioner. Especially, for the air conditioner that was used last
summer and re-used next spring and summer, the refrigerating effect of the air conditioner
is obviously worse than the previous year. What should be done is to dismantle the filter
screen of return air grille and filter screen of evaporator, and wash them. For preventing
such problem, it is necessary to regularly wash filter screen of the air conditioner according
to user’s manual. See aforesaid Item 4 of 3.3 for detailed requirements.
5. Abnormal sound of clutch
The fault is often related with bearing and behaviors as follows: when the engine starts up
while air conditioner is shutdown, the clutch makes abnormal sound, and after switch-on of
air conditioner, the abnormal sound disappears. Before pull-in of clutch, the bearing is in “full
working condition” when the load is the maximum. When the problem arises for the first
time, please contact SONGZ service center as soon as possible.
6. See User’s Manual for common troubleshooting of engine.
Air outlet
Fuse of
evaporator fan
Control box of return air inlet

28
Appendix: Fault analysis table of air conditioner for passenger vehicle
Fault analysis table: power-down of air conditioner
Fault Symptom Potential Cause Measure
Power-
down of air
conditioner
No air supply, no refrigeration,
and no panel display
No power input at Pin D+
on the manipulator of the air
conditioner
Check vehicle key switch
for the introduced power
supply
10A fuse of manipulator
damaged
Replace the fuse after
removing short circuit
and poor contact
Master fuse of power supply
burnt out, resulting in dead
power supply of electrical
load.
Same as
Manipulator failure Replace manipulator
No air supply and no
refrigeration
Generator failure (inside
regulator and generator)
Replace manipulator or
generator
Ineffective refrigerating output,
ineffective ventilating output,
effective excitation, ineffective
fresh air/ sterilization/heating,
and on the panel, only the low-
speed light keeps on.
(Supply) voltage higher than
+32VDC for consecutive
13s, resulting in too high
voltage of vehicle generator.
Check and replace
regulator or generator
Ineffective refrigerating
output, ineffective ventilating
output, ineffective excitation,
ineffective fresh air/ steriliza-
tion/heating, no display on the
panel, and noisy fan
The interior part of vehicle
generator or regulator
damaged when higher than
+45VDC
Check and replace
regulator or generator
Fault analysis table: no air supply or less air volume
No air supply or
less air volume
Evaporator fan fails
Poor grounding of fan Check circuit
Loose socket connectors Re-connect and fix
Broken fuse Replace fuse
Broken relay Replace relay
Broken speed regulation
resistance
Replace speed regulation
resistance
Broken evaporator fan Replace evaporator fan
Less air volume of air
outlet
Extremely dirty filter screen
of evaporator
Wash filter screen
Air pipe fallen off, causing
air leakage
Check the tightness of air
pipe
Electric brush of evaporator
fan seriously worn down
Replace carbon brush or
evaporator fan
Air volume has no change
when adjusting air volume
level
Manipulator failure
Check and replace
manipulator
The ventilation of
air conditioner is not
controlled by manipulator:
after switch-off of the air
conditioner, there is still air
supply from the air outlet.
Relay of the fan burnt out
with pins 30, 87 closed
Note: the fault always
occurs on the vehicle where
air conditioner and vehicle
share one generator.
Check and replace relay

30
Fault analysis table: no refrigeration
No refrigeration, only
natural wind supply
Compressor and condenser fan
fail
Carriage temperature is too
high or too low, i.e. higher
than 60°C or lower than 16°C
It is normal, with no need of
repair
The output voltage of
generator lower than 20V
Find the reason of low
pressure and treat the fault
fail, fault light shows red, and
high/low pressure is on the
low side.
Refrigerant in extremely low
volume
Check air leakage position and
add right amount of refrigerant
fail, fault light shows red, and
it’s difficult to set high/low
pressure
Refrigerant fully leaked
Check air leakage position and
add right amount of refrigerant
fail, fault light shows red, low
pressure is unusually low, and
filter pipe of receiver dryer is
condensed.
Receiver dryer blockage (by
dirt)
Dismantle and check the
component
fail, and fault light shows red
Return air temperature sensor
(temperature sensor) breakage
(open circuit)
Replace the sensors after
verifying the sensor is
defective.
Defrosting sensor breakage
(open circuit)
Same as above
Pressure switch defection
Replace the pressure switch
after verifying the switch is
defective
Compressor and condenser
fan fail, fault light shows red,
and high pressure is unusually
high.
Condenser fan breakage
Repair or replace the
condenser fan
Fuse of condenser fan burnt
out
Replace the fuse of condenser
fan
Compressor fails
Loosen socket connector of
electromagnetic clutch
Re-connect the cable of
compressor
Fuse of electromagnetic clutch
burnt out
Remove the reason of fuse
burnt out and replace the fuse
Control relay of
breakage
Replace the relay
Electromagnetic clutch
breakage
Repair or replace
Overly wider air gap of
Adjust air gap or replace the
clutch
Interior parts of compressor
damaged
Replace compressor
Loosen or broken transmission
belt
Adjust or replace the belt
intermittent
refrigeration
of air
conditioner
(cooling air
is just blown
out every
now and
then)
No pull-in of clutch
sometimes
Loose wire terminals of
Reconnect the wire, and replace
the electromagnetic clutch after
verifying the clutch is defective.
Defective Sensor (return air
temperature sensor and defrosting
sensor)
Replace the sensor after verifying
the sensor is defective.
Defective pressure switch that starts
to work under abnormal pressure
Replace the pressure switch after
verifying the switch is defective.
No closing of relay
sometimes
Relay of electromagnetic clutch
breakage
Replace the replay
The sensitivity of return air
temperature sensor or defrosting
sensor decreases or they installed in
incorrect position.
Adjust installation position of the
sensor; replace the sensor.
Insufficient
cooling air
Low pressure is unusually
low, or evaporator frosting
and air inlet of compressor
frosting may occur at the
same time.
The air flow passage in evaporator
blockage
Remove the blocking
Filter screen of return air grille of
evaporator blockage by dust or dirt.
Wash filter screen and remove the
blocking
Dirt in evaporator core Remove the dirt on evaporator core
Exhaust pressure is
unusually high, and
compressor is unusually
heating.
Dirt in condenser core, causing
blockage of air flow passage in
condenser
Wash out and remove the dirt on
condenser with compressed air or
water
The exhaust pressure
and suction pressure at
compressor side is high
Condenser fan failure
Remove the fault causing the fan
doesn’t work
The revolving speed of
condenser fan is slow, and
exhaust/suction pressure is
high.
Carbon brush seriously damaged Replace carbon brush or fan
Poor grounding of condenser fan Re-grounding
High/low pressure is on
low side, refrigerant is
not enough, and there are
obvious bubbles in sight
glass.
Refrigerant leakage Repair position with refrigerant
leakage, and then fill refrigerant till
to specified amount.
Leakage of system pipeline
Insufficient filling-up of refrigerant Fill refrigerant
High/low pressure is on
high side, there are bubbles
in sight glass, compressor
is noisy, and compressor is
unusually heating
Incondensable gas in the system: air,
hydrogen, nitrogen, etc. All the gases
circulate in system with refrigerant,
and don’t condense with refrigerant,
and don’t produce refrigerating
effect. Generally it is because of
incomplete vacuation, with some air
left in system.
Exhaust the incondensable gases,
and completely vacuate prior to
filling-up of refrigerant.
Compressor is noisy
The refrigerant oil is too much in the
system (note: refrigerant oil involves
in the circulation, but is not used as
heat exchange medium).
Check and adjust oil level of the
compressor
High pressure is low while
low pressure is high,
high/low pressure rapidly
keeps balanced after closing
refrigeration, compressor
is noisy and compressor is
unusually heating.
Compressor valve damaged and
existsing displacing valve leakage
(blowing between high and low
pressure cylinders)
Replace valve plate or compressor
Sealing gasket of valve plate
breakage (blowing between high and
low pressure cylinders)
Replace sealing gasket
Fault analysis table: insufficient cooling air

32
Fault analysis table: abnormal noise
Noise of actuating
device
After switch-on of air
conditioner, abnormal
noise comes out of
actuating part.
Sound from transition wheel
or tense bearing
Replace the transition
wheel or bearing
Sound from clutch bearing Replace clutch or bearing
Engine surges: Overly low
idle speed
Increase the idle speed of
engine
Loose support screw of
compressor
Adjust screw torsion
Belt slipped due to being
loose
Adjust belt intensity
Abnormal noise of
compressor
High/low pressure
is unusually high,
compressor is
unusually heating, and
compressor is noisy.
Too much refrigerant filled in
Discharge right amount of
refrigerant
Refrigerant oil is too
much
Too much refrigerant oil in
the system
Reduce the level of
compressor refrigerant oil
and make adjustment
Compressor is
unusually noisy
Liquid refrigerant flowed into
the compressor
See “Fault analysis table:
cooling air is not enough”
Interior of compressor
damaged
Replace compressor
Clutch slips on friction
surface
Excessive gap of clutch
Overly low voltage of
generator
See “Fault analysis table:
No refrigeration, but
normal ventilation”
Sound of fan Fan makes sound Sound from Fan bearing Replace the fan
Insufficient
cooling air
High/low pressure difference is
reduced
Overly large friction loss
between the parts inside
compressor, resulting in actual
air displacement much less than
theoretical one.
Repair or replace compressor
Low pressure is too low, and
obvious temperature difference
exists between the pipelines at
both sides, with drop of water on
the pipelines.
Receiver dryer inlet blockage Wash or replace drying filter
The displacing valve of
compressor breakage with
fragments entered into high
pressure end, resulting in slight
blocking.
Remove the fragments
Suction pressure is unusually
low, expansion valve frosts, the
low-pressure side sometimes
becomes vacuum, refrigeration
is intermittent or there is no
refrigeration at times, and pointer
of pressure gage jitters.
The water entering the system
iced at expansion valve nozzle,
stopping the circulation, but when
the ice is melted, the system
recovers its normal operation.
Generally, the problem arises
from the dryer in saturate status
and system moisture out of limit.
Clean or replace component, and
the dryer should be replaced.
Suction pressure is unusually low,
expansion valve frosts, and air
inlet of compressor frosts.
Damage or breakage in the
refrigerant pipeline between
thermal bulb of expansion valve
and the expansion valve
Check and replace expansion
valve and pipeline
Low pressure is high, or at the
same time, evaporator frosts, air
inlet of compressor frosts and
compressor becomes noisy.
Expansion valve overly opened.
Check if thermal bulb is fit with
outlet pipe of evaporator, and if
the installation position is correct.
Replace it as necessary.
The pressure on low pressure side
is low
Expansion valve overly closed:
interior balance pipe (thermal
bulb) breakage; dirty interior of
the valve.
Replace the thermal bulb or
expansion valve; wash the
expansion valve.
The pressure of low pressure pipe
is unusually high, evaporator
frosts, compressor frosts, and
compressor become noisy.
Expansion valve failure with
acicular corrosion or breakage.
Replace the expansion valve
Cooling air is not enough
The air flow of air outlets and
return air inlet shorted.
Block the air outlets on both sides
of return air inlet
Poor seal of evaporator box.
Cooling air is not enough Overly low speed of engine
Increase the speed of engine to
appropriate range
Cooling air is not enough
Polluted interior of system caused
by impure refrigerant
Replace refrigerant and refrigerant
oil
The temperature inside vehicle is
set too high.
Misuse: stop refrigeration before
human comfortable temperature
is reached.
Re-set temperature
Air outlets are too few, and the air
supply in carriage is too less.
Problems due to unreasonable air
passage structure with insufficient
air supply area.
Increase the number of air outlets
Heat insulation of platform floor
is poor
Metal floor without installation
of plastic board or PVC artificial
leather.
Install floor leather
There is no heat preservation
pasted in air passage.
Poor seal of air supply pipe. paste heat preservation
Air leakage exists in air passage.
Air pipe fallen off or the hot
airflow from outside entered into
the air passage.
Check and take appropriate
sealing measure

34
Common Used Circuit Diagram
1. The circuit diagrams in the Manual that represent part of products’ typical circuit diagrams.
2. Instruction for usage of circuit diagrams:
The circuit diagram SZC provided below is applicable to the maintenance of CPP, BBP, LUX
series. The so-called circuit difference between SZC-II, II/F, III, III/F, IV, IV/F, V, V/F, VI
series is just due to the variation of coil quantity of relay, evaporator fan, condenser fan and
compressor with same control principles.

36

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