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Electrical Controls and Safety Flashcards

6 cards from real HVAC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Electrical Controls and Safety flashcards as text

  1. What is a low ambient kit and when is it needed for air conditioning systems?

    Answer: Controls that allow a cooling system to operate properly at low outdoor temperatures

    A low ambient kit includes controls (head pressure controls, condenser fan cycling) that maintain proper condensing pressure when the system must operate in cool outdoor temperatures.

  2. What does a dual-capacitor (dual-run capacitor) contain and what does it power?

    Answer: Two separate capacitor sections in one housing: one for the compressor and one for the condenser fan motor

    A dual-run capacitor contains two separate capacitor sections in one round or oval housing, with one section running the compressor and the other running the condenser fan motor.

  3. What is the function of a crankcase pressure regulator (CPR) valve?

    Answer: Prevents excessive suction pressure from reaching the compressor on startup or during high-load conditions

    A CPR valve limits the suction pressure entering the compressor to protect it from overload conditions during pulldown or high-load startup situations.

  4. What does a digital multimeter's 'uF' setting measure on a capacitor?

    Answer: Microfarads — the capacitance value of the capacitor

    The uF (microfarad) setting on a multimeter measures a capacitor's capacitance value, allowing technicians to verify the capacitor meets its rated specification.

  5. In an HVAC system, what does 'single phasing' refer to in a three-phase motor?

    Answer: Loss of one of three power phases causing the motor to overheat and fail

    Single phasing occurs when one of three phases is lost (open fuse, broken wire), causing the motor to try to run on two phases, drawing excessive current and overheating.

  6. What is the purpose of a compressor hard start kit?

    Answer: To provide extra starting torque using a start capacitor and potential relay when the compressor struggles to start

    A hard start kit adds a start capacitor and potential relay to boost starting torque for compressors that struggle to start, often due to voltage issues or worn motor windings.