The document provides an overview of the main components that make up an automotive cooling system. It describes the purpose of the cooling system is to regulate engine temperature and remove excess heat. The key components that are discussed include the water pump, cooling fans, radiator, thermostat, coolant, and heater core. Various types of each component are also outlined, such as belt driven and electric cooling fans as well as how components work together to efficiently cool the engine.

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. Overview