Practice Test Geeks(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test
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Electrical Systems and Controls Flashcards

7 cards from real 313D practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Electrical Systems and Controls flashcards as text

  1. A residential AC system uses a dual run capacitor. Which terminals are typically labeled on this component?

    Answer: C (common), FAN, HERM

    A dual run capacitor has three terminals: C (common), HERM (compressor/hermetic), and FAN (condenser fan motor).

  2. What is the function of a hard start kit (potential relay and start capacitor) added to an existing AC compressor?

    Answer: Increase starting torque to help the compressor start under difficult conditions

    A hard start kit adds extra starting torque, which is helpful when supply voltage is low, refrigerant pressures are unequalized, or the compressor is aging.

  3. An ECM blower motor in a residential air handler is different from a PSC motor because it:

    Answer: Uses a variable-speed DC motor controlled by an integrated module

    ECM (Electronically Commutated Motor) motors use a built-in inverter and brushless DC technology to vary speed efficiently.

  4. When using a clamp-on ammeter to measure compressor current, you clamp around only one power conductor. Why?

    Answer: To measure the current in one leg without cancellation from opposing current flow

    Clamping around both conductors simultaneously causes the opposing magnetic fields to cancel out, resulting in a near-zero reading.

  5. A high-pressure switch in a residential AC system is wired in series with the:

    Answer: Compressor contactor coil circuit

    The high-pressure switch opens the control circuit to de-energize the contactor coil, shutting off the compressor when discharge pressure exceeds a safe limit.

  6. What reading would indicate a shorted run capacitor when tested with a capacitance meter?

    Answer: Reading of 0 µF or OL (overload/short)

    A shorted capacitor shows 0 µF or an OL symbol on a capacitance meter because the internal dielectric has broken down completely.

  7. In residential AC electrical schematics, a dashed line between two components typically indicates:

    Answer: A mechanical linkage or shared enclosure

    Dashed lines in schematics represent mechanical connections or components physically housed together, not electrical conductors.