HVAC Electrical Test Questions and
Answers | Latest Version | 2025/2026 |
Correct & Verified
Why are relays often used with thermostats?
✔✔To control high-voltage equipment with low-voltage thermostat signals.
What is a short circuit?
✔✔An unintended low-resistance path allowing excessive current flow.
Why is it important to turn off power before servicing HVAC equipment?
✔✔To prevent electrical shock and equipment damage.
What is the role of a blower motor capacitor?
✔✔To help start and run the blower motor efficiently.
What is an ammeter used for?
✔✔To measure current flow in a circuit.
Why is insulation resistance testing important?
✔✔To detect deteriorated wiring that could cause shorts or shock.
What is a typical symptom of a bad contactor coil?
1
,✔✔The unit fails to start, even though power is supplied.
Why is voltage drop a concern in HVAC wiring?
✔✔Excessive voltage drop can reduce equipment performance and cause overheating.
What is the purpose of a reversing valve solenoid in a heat pump?
✔✔To switch the system between heating and cooling modes.
Why is a transformer polarity important in HVAC controls?
✔✔Incorrect polarity can cause malfunction or damage to control devices.
What is the function of a defrost control board in a heat pump?
✔✔To initiate and terminate defrost cycles for efficient operation.
Why is a surge protector recommended for HVAC systems?
✔✔To protect equipment from voltage spikes and lightning surges.
What is the primary function of a capacitor in an HVAC motor circuit?
✔✔To store and release electrical energy to help start and run the motor efficiently.
What does a contactor do in an HVAC system?
✔✔It switches high-voltage power to the compressor or condenser fan.
2
, Why is grounding important in HVAC electrical systems?
✔✔To protect personnel and equipment from electrical hazards.
What is the function of a transformer in an HVAC system?
✔✔To step down voltage to operate control circuits safely.
Why is a circuit breaker used in HVAC electrical systems?
✔✔To protect the circuit from overcurrent or short circuits.
What is a common symptom of a failed capacitor?
✔✔Motor hums but does not start or runs weakly.
Why are fuses used in HVAC equipment?
✔✔To protect circuits from overcurrent by melting and breaking the circuit.
What is the purpose of a relay in HVAC controls?
✔✔To allow a low-voltage circuit to control a high-voltage circuit.
What is an overload protector in an HVAC motor?
✔✔A device that shuts off the motor if it draws too much current.
3
Answers | Latest Version | 2025/2026 |
Correct & Verified
Why are relays often used with thermostats?
✔✔To control high-voltage equipment with low-voltage thermostat signals.
What is a short circuit?
✔✔An unintended low-resistance path allowing excessive current flow.
Why is it important to turn off power before servicing HVAC equipment?
✔✔To prevent electrical shock and equipment damage.
What is the role of a blower motor capacitor?
✔✔To help start and run the blower motor efficiently.
What is an ammeter used for?
✔✔To measure current flow in a circuit.
Why is insulation resistance testing important?
✔✔To detect deteriorated wiring that could cause shorts or shock.
What is a typical symptom of a bad contactor coil?
1
,✔✔The unit fails to start, even though power is supplied.
Why is voltage drop a concern in HVAC wiring?
✔✔Excessive voltage drop can reduce equipment performance and cause overheating.
What is the purpose of a reversing valve solenoid in a heat pump?
✔✔To switch the system between heating and cooling modes.
Why is a transformer polarity important in HVAC controls?
✔✔Incorrect polarity can cause malfunction or damage to control devices.
What is the function of a defrost control board in a heat pump?
✔✔To initiate and terminate defrost cycles for efficient operation.
Why is a surge protector recommended for HVAC systems?
✔✔To protect equipment from voltage spikes and lightning surges.
What is the primary function of a capacitor in an HVAC motor circuit?
✔✔To store and release electrical energy to help start and run the motor efficiently.
What does a contactor do in an HVAC system?
✔✔It switches high-voltage power to the compressor or condenser fan.
2
, Why is grounding important in HVAC electrical systems?
✔✔To protect personnel and equipment from electrical hazards.
What is the function of a transformer in an HVAC system?
✔✔To step down voltage to operate control circuits safely.
Why is a circuit breaker used in HVAC electrical systems?
✔✔To protect the circuit from overcurrent or short circuits.
What is a common symptom of a failed capacitor?
✔✔Motor hums but does not start or runs weakly.
Why are fuses used in HVAC equipment?
✔✔To protect circuits from overcurrent by melting and breaking the circuit.
What is the purpose of a relay in HVAC controls?
✔✔To allow a low-voltage circuit to control a high-voltage circuit.
What is an overload protector in an HVAC motor?
✔✔A device that shuts off the motor if it draws too much current.
3
