CFESA Diagnostic Troubleshooting 1 — Questions and Answers
Question 1: A commercial refrigerator compressor runs continuously but the cabinet temperature is too warm. After confirming proper refrigerant charge and airflow, the technician should next check:
- The door gaskets and thermostat calibration (Correct answer)
- The condenser fan blade pitch
- The compressor motor winding resistance
- The liquid line filter drier color indicator
Correct answer: The door gaskets and thermostat calibration
Leaking door gaskets allow warm air infiltration, and an out-of-calibration thermostat may not cycle the compressor correctly — both cause continuous running without reaching setpoint.
Question 2: When using a clamp meter to diagnose a commercial cooking appliance, a technician measures amp draw significantly above nameplate rating. This indicates:
- The equipment is operating normally under full load
- A possible short circuit, failed component drawing excess current, or mechanical binding (Correct answer)
- The circuit breaker is undersized
- The power supply voltage is too low
Correct answer: A possible short circuit, failed component drawing excess current, or mechanical binding
Amp draw significantly above nameplate rating indicates an electrical fault such as a short, a failed component, or mechanical resistance causing the motor to draw excess current.
Question 3: What is the correct method to test a commercial heating element for an open circuit?
- Apply power and measure temperature rise
- Use a multimeter set to resistance (ohms) to measure element resistance with power off (Correct answer)
- Use a clamp meter with power on
- Apply 120V and check for heat output
Correct answer: Use a multimeter set to resistance (ohms) to measure element resistance with power off
An ohmmeter measures the element's resistance with power disconnected; an open circuit reads infinite (OL) resistance, confirming the element has failed.
Question 4: A commercial ice machine produces small, misshapen ice cubes. The most likely cause is:
- Refrigerant overcharge
- Low water pressure or clogged water distribution tube (Correct answer)
- Faulty ice thickness probe
- Condenser fan running backward
Correct answer: Low water pressure or clogged water distribution tube
Inadequate water flow through the distribution tube causes incomplete ice cell formation, resulting in small, hollow, or misshapen cubes.
Question 5: A technician is called to service a commercial steamship round that will not heat. The first step in the diagnostic process should be:
- Replace the heating element
- Verify power supply voltage and check the thermostat for continuity (Correct answer)
- Check the water level probe
- Replace the temperature controller
Correct answer: Verify power supply voltage and check the thermostat for continuity
Diagnosing a no-heat condition starts with verifying proper voltage supply and then checking the control circuit (thermostat) for continuity before testing components.
Question 6: When diagnosing an intermittent fault on commercial food equipment, the most effective approach is:
- Replace all major components until the fault goes away
- Recreate the fault condition, monitor all relevant parameters, and use wiring diagrams to isolate the circuit (Correct answer)
- Wait for the fault to occur and observe the symptom only
- Replace the control board as it is the most likely cause of intermittent faults
Correct answer: Recreate the fault condition, monitor all relevant parameters, and use wiring diagrams to isolate the circuit
Intermittent faults require systematic diagnosis: recreating conditions that trigger the fault, measuring electrical parameters, and using schematics to isolate the faulty circuit.
CFESA Diagnostic Troubleshooting 1
A commercial refrigerator compressor runs continuously but the cabinet temperature is too warm.
After confirming proper refrigerant charge and airflow, the technician should next check: