CFESA Repair Techniques 2 — Questions and Answers
Question 1: When replacing a gas valve on a commercial range, what must be verified after installation before returning the unit to service?
- Check only the inlet pressure
- Leak test all connections with approved soap solution and verify proper outlet pressure (Correct answer)
- Visually inspect the valve body for cracks
- Confirm the pilot flame is lit
Correct answer: Leak test all connections with approved soap solution and verify proper outlet pressure
After replacing a gas valve, all connections must be leak-tested and outlet pressure verified to ensure safe, correct operation.
Question 2: A commercial convection oven's blower motor runs but the fan blade does not spin. What is the most likely cause?
- Failed run capacitor
- Tripped thermal overload
- Sheared motor shaft key or set screw (Correct answer)
- Open limit switch
Correct answer: Sheared motor shaft key or set screw
If the motor runs but the blade does not spin, a sheared key or loose set screw has disconnected the blade from the shaft.
Question 3: Which technique is used to identify a cracked heat exchanger in a commercial gas fryer?
- Apply high voltage to the exchanger surface
- Pressurize the heat exchanger with nitrogen and check for bubbles in the oil (Correct answer)
- Use a multimeter to measure resistance across the exchanger
- Inspect visually only under bright light
Correct answer: Pressurize the heat exchanger with nitrogen and check for bubbles in the oil
Pressurizing the heat exchanger with nitrogen and submerging or coating with soap solution reveals cracks through bubble formation.
Question 4: When soldering refrigerant tubing on a commercial ice machine, which gas should be flowed through the tubing to prevent internal oxidation?
- Carbon dioxide
- Oxygen
- Dry nitrogen (Correct answer)
- Argon
Correct answer: Dry nitrogen
Flowing dry nitrogen through refrigerant tubing during soldering prevents copper oxide scale formation inside the lines.
Question 5: A steam kettle is producing insufficient steam pressure. After confirming adequate water supply, what is the next diagnostic step?
- Replace the heating elements immediately
- Check and clean the steam generator scale buildup and inspect the safety valve (Correct answer)
- Adjust the thermostat to maximum
- Inspect the lid gasket only
Correct answer: Check and clean the steam generator scale buildup and inspect the safety valve
Scale buildup in the steam generator reduces heat transfer efficiency, and a faulty safety valve can bleed off pressure before it builds properly.
Question 6: What is the correct procedure for re-torquing cylinder head bolts on a commercial food equipment compressor after initial repair?
- Torque cold in a star pattern to spec, then recheck after first thermal cycle (Correct answer)
- Torque hot in a circular pattern to maximum
- Torque once cold and do not recheck
- Torque only the perimeter bolts
Correct answer: Torque cold in a star pattern to spec, then recheck after first thermal cycle
Cylinder head bolts should be torqued cold in a star pattern per spec, then re-torqued after the first heat cycle to compensate for material relaxation.
Question 7: A technician finds a commercial dishwasher wash arm delivering uneven spray. After clearing visible debris, the problem persists. What should be checked next?
- The detergent dispenser timing
- Wash arm bearing or pivot wear causing misalignment (Correct answer)
- The rinse aid concentration
- Door switch continuity
Correct answer: Wash arm bearing or pivot wear causing misalignment
Worn wash arm bearings or pivot seats allow the arm to wobble or sit off-center, causing uneven spray even when ports are clear.
CFESA Repair Techniques 2
When replacing a gas valve on a commercial range, what must be verified after installation before returning the unit to service?