Practice Test Geeks(CRST) Certified Refrigeration Service Technician Practice Test
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Troubleshooting & Repair Techniques Flashcards

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

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  1. A refrigeration system is short-cycling on the low-pressure control. What is the MOST likely cause?

    Answer: Low refrigerant charge

    A low refrigerant charge causes suction pressure to drop below the low-pressure control cutout setpoint, causing repeated short cycling.

  2. A technician measures a 15°F superheat at the evaporator outlet and 80°F subcooling at the condenser outlet. What condition does this indicate?

    Answer: Refrigerant overcharge

    Excessive subcooling combined with normal or low superheat is a classic sign of refrigerant overcharge in the system.

  3. When checking a hermetic compressor for an open motor winding, which instrument should be used?

    Answer: Ohmmeter

    An ohmmeter measures resistance between terminals to identify an open winding, which shows infinite or very high resistance.

  4. A walk-in cooler is not maintaining setpoint even though the compressor runs continuously. The evaporator coil is heavily frosted. What is the FIRST action to take?

    Answer: Defrost the evaporator coil

    Heavy frost blocks airflow across the evaporator, reducing heat transfer efficiency; defrosting restores normal operation before further diagnosis.

  5. Oil logging in the evaporator of a low-temperature system is MOST likely caused by:

    Answer: Insufficient refrigerant velocity to return oil

    At low temperatures, refrigerant vapor density decreases, and if velocity is too low, oil cannot be carried back to the compressor crankcase.

  6. A system has high head pressure and low suction pressure. The superheat is normal and subcooling is low. What is the MOST probable cause?

    Answer: Restricted metering device

    A restricted metering device causes high head pressure upstream and starves the evaporator, resulting in low suction pressure and low subcooling.

  7. A technician finds the compressor discharge temperature is 280°F. What is the MOST likely cause?

    Answer: High superheat due to low suction pressure

    Excessive superheat entering the compressor raises compression temperature dramatically, often caused by low refrigerant or high evaporator load.