Michigan Mechanic Certification- HVAC
Questions & Answers
1. Cooling system leak diagnosis
Answer Pressure test or dye test
2. 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
3. Symptoms of low coolant
Answer Engine overheating and no heat from the HVAC system
4. Purpose of the thermostat
Answer The purpose of the thermostat is to trap the coolant in the engine until it reaches it operating
temperature
5. Cause of low heater output
Answer Low coolant level, clogged heater core, leaking heater core
6. 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
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, 7. Heater core operation
Answer The blower motor blows air through the heater core fins and is warmed through the principle of
conduction
8. 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
9. 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
10. Reciever drier purpose
Answer May contain a filter or strainer to catch and trap foreign particles and dirt
11. Reciever drier location
Answer Located on the high side of the system between the condenser and the evaporator
12. Ambient temperature switch purpose
Answer Monitors temperature by increasing or decreasing with resistance as temperature changes
13. Symptoms of a failing ambient temperature switch
Answer A bad temperature switch could cause an inoperative clutch or input problems
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Questions & Answers
1. Cooling system leak diagnosis
Answer Pressure test or dye test
2. 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
3. Symptoms of low coolant
Answer Engine overheating and no heat from the HVAC system
4. Purpose of the thermostat
Answer The purpose of the thermostat is to trap the coolant in the engine until it reaches it operating
temperature
5. Cause of low heater output
Answer Low coolant level, clogged heater core, leaking heater core
6. 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
1/
6
, 7. Heater core operation
Answer The blower motor blows air through the heater core fins and is warmed through the principle of
conduction
8. 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
9. 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
10. Reciever drier purpose
Answer May contain a filter or strainer to catch and trap foreign particles and dirt
11. Reciever drier location
Answer Located on the high side of the system between the condenser and the evaporator
12. Ambient temperature switch purpose
Answer Monitors temperature by increasing or decreasing with resistance as temperature changes
13. Symptoms of a failing ambient temperature switch
Answer A bad temperature switch could cause an inoperative clutch or input problems
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