This document summarizes the key components of an automobile cooling system and how they work together. The main components are the water pump, cooling fan, radiator, thermostat, coolant, and heater core. The water pump circulates coolant throughout the system at high volumes to regulate the engine's temperature. The cooling fan provides airflow through the radiator to dissipate heat into the atmosphere. Sensors and the engine control module monitor temperatures and control electric cooling fans and fan clutches to maintain optimal operating temperatures.

1. THE COOLING SYSTEM

2. Purpose
• To regulate the engines internal
temperature
• To remove excess heat from the engine
• To provide heat to the passenger
compartment

3. The Water Pump
• Centrifugal-type,
rotates faster than
crank, up to
10,000 gal. per
hour
• Pulley driven, belt,
chain drive or
direct drive

4. The Cooling Fan
• Provides air flow
with vehicle stopped
• Provides increased
air flow at low RPM
or vehicle speeds
• Belt driven or
Electric

5. Belt Driven Cooling Fan Clutch
• Limits actual fan speed
no more than 2000 rpm
• Engaged at low speeds
• Disengaged at high
speeds
• Thermostatic (temp.
sensitive)

6. Flex Blade Fan
• Fan blades
flatten out at
high
speeds,
reducing
noise,
increasing
horse power

7. Electric Cooling Fan
• Electric – 12v DC motor
driven fan
• Controlled in several ways
– Engine coolant temp (ECT)
switch
– A/C select switch
– PCM controlled based on
various inputs
• Fan turns on/off at specific
temps.

8. Electro-Viscous Fan Clutch
• PCM Controlled fan
speed
• Sensors monitored to
control speed:
– ECT, A/C request,
VSS, IAT, Trans Fluid
Temp, AAT
• Solenoid controls fluid
flow, regulating fan
speed
• Internal hall effect sensor
monitors fan speed

9. The Radiator
• Transfers heat from coolant to the
atmosphere
• Two types – Vertical & cross flow
• Aluminum, brass, copper core; brass,
copper or plastic tanks
• Air movement through radiator created
by a mechanical fan or by vehicle
movement (ram air) dissipates heat

10. How a Radiator Works

11. Radiator Pressure Cap
• Regulates pressure in the cooling
system
• Rated in psi – always replace with same
rating
• Pressure valve – allows liquid or vapor
to escape
• Vacuum valve – as system cools,
coolant can reenter the system

13. The Thermostat
• Regulates engine coolant temperature
• Rated in degrees – 195 degrees most
common
• Solid Expansion design – wax pellet
expands as temp increases, valve
begins opening at rating & is completely
open within 20 degrees

15. Coolant
• Provides freeze & boil over protection,
corrosion prevention & good heat
transfer
• Ethylene Glycol based – recommended
50/50 mixture with water, poisonous
• Dex-Cool – used by GM, 5 year
150,000 mile protection, doesn’t contain
silicate & phosphate additives

16. The Heater Core
• Small size radiator located in the dash,
coolant circulates through it. A blower
motor passes fresh air over it, heat
transfers to the cooler air and into the
cabin
• Many vans & SUV have rear heating
units

18. OLD
NEW

19. Overvie
w

20. SUBMITTED BY:ASHU RANJAN
ROLL NO