Michigan Mechanic Certification- HVAC Questions and Correct
Answers (100% Pass)
Cooling system leak diagnosis
Pressure test or dye test
Purpose of a radiator
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
Engine overheating and no heat from the HVAC system
Purpose of the thermostat
The purpose of the thermostat is to trap the coolant in the engine until it reaches it operating
temperature
Cause of low heater output
Low coolant level, clogged heater core, leaking heater core
Heater core hose routing
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
The blower motor blows air through the heater core fins and is warmed through the principle of
conduction
Heater control valve purpose
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
To test pressure test it using an adapter and a coolant pressure tester and the value marked on the
pressure cap
Reciever drier purpose
May contain a filter or strainer to catch and trap foreign particles and dirt
Reciever drier location
Located on the high side of the system between the condenser and the evaporator
Ambient temperature switch purpose
Page 1 of 4
Answers (100% Pass)
Cooling system leak diagnosis
Pressure test or dye test
Purpose of a radiator
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
Engine overheating and no heat from the HVAC system
Purpose of the thermostat
The purpose of the thermostat is to trap the coolant in the engine until it reaches it operating
temperature
Cause of low heater output
Low coolant level, clogged heater core, leaking heater core
Heater core hose routing
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
The blower motor blows air through the heater core fins and is warmed through the principle of
conduction
Heater control valve purpose
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
To test pressure test it using an adapter and a coolant pressure tester and the value marked on the
pressure cap
Reciever drier purpose
May contain a filter or strainer to catch and trap foreign particles and dirt
Reciever drier location
Located on the high side of the system between the condenser and the evaporator
Ambient temperature switch purpose
Page 1 of 4
