COOLING AND COMFORT HEATING SYSTEMS CHAPTER 3 Page 54 Classroom Manual Page 56 Lab Manual

ENGINE HEAT u Normal operation produces heat that must be carried away by coolant u Accomplished by Conduction, Convection and Radiation u Coolant transfers heat to less hot outside air. u Coolant does not change state as with A/C Pg... 44C

COOLING SYSTEM OPERATION u System design removes 35% of total heat u If not equipped with factory A/C, cooling system usually not able to handle additional heat load u Uses Radiator to transfer heat. Most radiators about sq. feet.

COMPONENTS u 5 COOLING SYSTEM COMPONENTS –Water Pump –Cooling Fan –Radiator –Pressure Cap –Thermostat

RADIATORS u Two Types Pg. 47C –Vertical Flow Tubular Construction –Cross Flow Cellular Construction u PRESSURE CAPS –Equipped with Vacuum and Pressure Valve –Used to raise Pressure in system u Radiator Diagnosis u Radiator Repair Pg C Pg L

WATER PUMPS u Centrifugal Type Water Pump u Inlet comes from bottom of Radiator u Outlet is through impeller to engine u Allows circulation when thermostat is closed u Water Pump Replacement is usually due to leaks u Transfer pump parts and use correct gaskets Pg C Pg L

PULLEYS AND BELTS u Pitch and Width must be correct u Tension belt in foot pounds u Serpentine Belts and Diagrams u Some water pumps turn in opposite direction Pg & 234C

THERMOSTATS u Senses coolant temperature and regulates temperature u Part of cooling system design u Temperature should not be changed u Stat will not cause overheating unless it is defective u Stat will not cause overcooling unless bad Pg C Pg L

COOLING FANS u Engine driven fans u Fan Clutch - Speed limiting & Heat Sensing u Flexible Fans u Electric Fans - Can operate anytime u Fans are necessary for low speed operation u Can be Clockwise or CCW u Diagnosis and Inspection Pg C Pg L

HOSES AND CLAMPS u Made of oil and ozone resistant reinforced synthetic rubber u Performed Hoses u Flexible hoses u Worm gear type hose clamps u If one hose is bad, usually a good idea to replace all hoses u Clamp Placement must be correct Pg C Pg L

ANTI-FREEZE AND ADDITIVES u Ethylene glycol based - Good for 1-2 yr u 50/50% solution recommended –Lowers Freezing Point –Raises Boiling Point –Provides lubrication –Inhibits Rust and Corrosion u Protection Chart Pg L u Testing (Strength and Electrolysis) Pg C Pg L

PREVENTATIVE MAINTENANCE u Every 12K to 15K miles perform cooling system maintenance u Replace belts if bad u Replace antifreeze 50/50 mixture u Pressure Testing System u Check Fan operation

DIAGNOSIS u Radiator u Water Control Valve u Water Pump u Thermostat u Cooling System Leaks u Electrical Related System Page L