Practice Test Geeks(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test
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Electrical Components and Wiring 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 Components and Wiring flashcards as text

  1. Which electrical test would BEST confirm that a compressor motor winding has a ground fault?

    Answer: Measure resistance between each winding terminal and the compressor shell/ground

    A megohmmeter or ohmmeter reading between a winding terminal and the grounded shell detects insulation breakdown indicating a ground fault.

  2. A residential condensing unit's nameplate lists MOCP as 35 amps. A technician installs a 40-amp breaker. This installation is:

    Answer: A code violation because the breaker exceeds the maximum listed on the nameplate

    Installing a breaker larger than the MOCP listed on the nameplate violates NEC 440.22 and the unit's listing, removing the equipment's certified overcurrent protection.

  3. What is the purpose of the time-delay relay (TDR) found in some residential AC control circuits?

    Answer: Prevents compressor short-cycling by enforcing a minimum off time between starts

    A TDR enforces a compressor off-delay (typically 3–5 minutes) to allow pressures to equalize, preventing motor damage from trying to start against unequalized head pressure.

  4. When installing low-voltage thermostat wire, what is the minimum recommended AWG size for runs up to 100 feet?

    Answer: 18 AWG

    18 AWG is the industry standard for thermostat wire runs up to approximately 100 feet, providing sufficient conductance to avoid excessive voltage drop in the 24V circuit.

  5. A residential AC system trips the breaker repeatedly after running for 10–15 minutes. The MOST likely electrical cause is:

    Answer: Compressor drawing excessive amperage due to a failing motor or refrigerant overcharge

    Thermal trip after a short run time typically indicates the compressor is drawing above-normal current, which could be caused by a failing motor winding or an overcharged refrigerant system.

  6. What does the 'W' terminal on a residential thermostat control?

    Answer: Heating (furnace or heat pump) circuit

    The W terminal carries the heat call signal, energizing the furnace burner, electric heat strips, or heat pump reversing valve depending on the system type.

  7. A technician is connecting a new condenser fan motor and notices the motor has five leads. Which tool or resource should be used to determine the correct wiring configuration?

    Answer: The motor manufacturer's wiring diagram printed on the motor label or data sheet

    Multi-lead motors have specific wiring configurations for different voltages and speeds, which are always documented on the motor's label or accompanying data sheet.