HVAC Electrical Test Questions and Answers | Latest Version | 2025/2026 | Correct & Verified

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? 2 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. 3 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. 4 What is the difference between single-phase and three-phase power? Single-phase power has one alternating voltage, three-phase has three, providing smoother power for large motors. Why should all HVAC electrical connections be tight? Loose connections cause resistance, heat, and potential failure. What is the purpose of a disconnect switch? To safely isolate the HVAC unit for service. What does a multimeter measure? Voltage, current, and resistance in electrical circuits. What is the function of a thermostat in electrical terms? It acts as a switch to open or close