Michigan Mechanic Certification- HVAC
Cooling system leak diagnosis - answer Pressure test or dye test
Purpose of a radiator - answer The purpose of the radiator is to dissipate heat that is picked up by coolant in the engine into the air passing through its fins and tubes
Symptoms of low coolant - answer Engine overheating and no heat from the HVAC system
Purpose of the thermostat - answer The purpose of the thermostat is to trap the coolant in the engine until it reaches it operating temperature
Cause of low heater output - answer Low coolant level, clogged heater core, leaking heater core
Heater core hose routing - answer The supply hose from the heater core should run from the closed side of the thermostat to the heater core and the return hose should run
from the heater core to the engine
Heater core operation - answer The blower motor blows air through the heater core fins and is warmed through the principle of conduction
Heater control valve purpose - answer This valve controls the flow of the coolant to the heater core to control the temperature of the air desired by the operator
Radiator cap testing - answer To test pressure test it using an adapter and a coolant pressure tester and the value marked on the pressure cap
Reciever drier purpose - answer May contain a filter or strainer to catch and trap foreign particles and dirt
Reciever drier location - answer Located on the high side of the system between the condenser and the evaporator
Ambient temperature switch purpose - answer Monitors temperature by increasing or
decreasing with resistance as temperature changes
Symptoms of a failing ambient temperature switch - answer A bad temperature switch could cause an inoperative clutch or input problems
Cooling system leak diagnosis - answer Pressure test or dye test
Purpose of a radiator - answer The purpose of the radiator is to dissipate heat that is picked up by coolant in the engine into the air passing through its fins and tubes
Symptoms of low coolant - answer Engine overheating and no heat from the HVAC system
Purpose of the thermostat - answer The purpose of the thermostat is to trap the coolant in the engine until it reaches it operating temperature
Cause of low heater output - answer Low coolant level, clogged heater core, leaking heater core
Heater core hose routing - answer The supply hose from the heater core should run from the closed side of the thermostat to the heater core and the return hose should run
from the heater core to the engine
Heater core operation - answer The blower motor blows air through the heater core fins and is warmed through the principle of conduction
Heater control valve purpose - answer This valve controls the flow of the coolant to the heater core to control the temperature of the air desired by the operator
Radiator cap testing - answer To test pressure test it using an adapter and a coolant pressure tester and the value marked on the pressure cap
Reciever drier purpose - answer May contain a filter or strainer to catch and trap foreign particles and dirt
Reciever drier location - answer Located on the high side of the system between the condenser and the evaporator
Ambient temperature switch purpose - answer Monitors temperature by increasing or
decreasing with resistance as temperature changes
Symptoms of a failing ambient temperature switch - answer A bad temperature switch could cause an inoperative clutch or input problems
