MICHIGAN MECHANIC CERTIFICATION- HVAC QUESTIONS
& ANSWERS 2024 (A+ GRADED 100% VERIFIED)
1. Cooling system leak diagnosis: pressure test or dye test
2. 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
3. Symptoms of low coolant: engine overheating and no heat from the hvac
system
4. Purpose of the thermostat: 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: low coolant level, clogged heater core, leaking
heater core
6. 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
7. Heater core operation: the blower motor blows air through the heater core
fins and is warmed through the principle of conduction
8. 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
9. Radiator cap testing: 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: may contain a filter or strainer to catch and trap
foreign particles and dirt
11. Reciever drier location: located on the high side of the system between the
condenser and the evaporator
12. Ambient temperature switch purpose: monitors temperature by increasing
or decreasing with resistance as temperature changes
13. Symptoms of a failing ambient temperature switch: a bad temperature
switch could cause an inoperative clutch or input problems
14. Orifice expansion tube operation: has a valve that can vary the size of the
opening to allow more or less liquid refrigerant through to the evaporator
15. Orifice expansion tube purpose: high-pressure liquid enters, low-pressure
liquid leaves
16. Purpose of a compressor: low-pressure gas enters and high-pressure gas
leaves
17. Symptoms of a failing compressor: pressures are going to be equal
18. Purpose of a condenser: low-pressure gas enters and high-pressure gas
leaves
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& ANSWERS 2024 (A+ GRADED 100% VERIFIED)
1. Cooling system leak diagnosis: pressure test or dye test
2. 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
3. Symptoms of low coolant: engine overheating and no heat from the hvac
system
4. Purpose of the thermostat: 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: low coolant level, clogged heater core, leaking
heater core
6. 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
7. Heater core operation: the blower motor blows air through the heater core
fins and is warmed through the principle of conduction
8. 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
9. Radiator cap testing: 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: may contain a filter or strainer to catch and trap
foreign particles and dirt
11. Reciever drier location: located on the high side of the system between the
condenser and the evaporator
12. Ambient temperature switch purpose: monitors temperature by increasing
or decreasing with resistance as temperature changes
13. Symptoms of a failing ambient temperature switch: a bad temperature
switch could cause an inoperative clutch or input problems
14. Orifice expansion tube operation: has a valve that can vary the size of the
opening to allow more or less liquid refrigerant through to the evaporator
15. Orifice expansion tube purpose: high-pressure liquid enters, low-pressure
liquid leaves
16. Purpose of a compressor: low-pressure gas enters and high-pressure gas
leaves
17. Symptoms of a failing compressor: pressures are going to be equal
18. Purpose of a condenser: low-pressure gas enters and high-pressure gas
leaves
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