CAR Troubleshooting & Diagnostics 2 — Questions and Answers
Question 1: A refrigerator compressor runs continuously but the unit never reaches set temperature. What is the MOST likely cause?
- Faulty door gasket allowing warm air infiltration
- Defective thermostat set too high
- Refrigerant leak reducing system pressure (Correct answer)
- Clogged condenser coils reducing heat rejection
Correct answer: Refrigerant leak reducing system pressure
A refrigerant leak lowers system pressure, reducing the refrigerant's ability to absorb heat, so the compressor runs constantly without achieving proper cooling.
Question 2: When diagnosing a washing machine that vibrates excessively during the spin cycle, which component should be inspected first?
- Motor capacitor
- Drum bearing or shock absorbers (Correct answer)
- Water inlet valve
- Control board relay
Correct answer: Drum bearing or shock absorbers
Worn drum bearings or failed shock absorbers allow the drum to move erratically during high-speed spin, causing excessive vibration.
Question 3: A dryer heats normally but clothes remain damp after a full cycle. Which diagnostic step is MOST appropriate?
- Replace the heating element immediately
- Check and clean the exhaust vent for blockages (Correct answer)
- Test the motor capacitor with a multimeter
- Inspect the door switch continuity
Correct answer: Check and clean the exhaust vent for blockages
A blocked exhaust vent traps moist air inside the drum, preventing evaporation and leaving clothes damp despite normal heat output.
Question 4: Which instrument is used to measure insulation resistance in a motor winding to detect breakdown?
- Clamp-on ammeter
- Megohmmeter (Megger) (Correct answer)
- Oscilloscope
- Manometer
Correct answer: Megohmmeter (Megger)
A megohmmeter applies high voltage to measure insulation resistance in megaohms, revealing deterioration or breakdown in motor windings.
Question 5: A dishwasher fills with water but the wash arms do not spray. What is the MOST likely fault?
- Faulty heating element
- Blocked or clogged spray arm ports (Correct answer)
- Defective water inlet valve
- Failed door latch switch
Correct answer: Blocked or clogged spray arm ports
Clogged spray arm ports restrict water flow, preventing the rotation and spray action needed to clean dishes.
Question 6: An appliance technician notices a capacitor with a bulging top during inspection. What does this indicate?
- The capacitor is fully charged and functioning normally
- The capacitor has failed and must be replaced before recycling (Correct answer)
- The capacitor needs a discharge cycle before testing
- The capacitor is a high-voltage type requiring special handling only
Correct answer: The capacitor has failed and must be replaced before recycling
A bulging capacitor top is a clear sign of internal gas buildup from failure, meaning the component is defective and must be replaced or safely disposed of.
Question 7: When testing a refrigerator start relay, a rattling sound when shaken indicates what?
- The relay is functioning correctly with normal internal movement
- The relay is an overload protector, not a start relay
- The internal contact is broken and the relay has failed (Correct answer)
- The relay requires lubrication before testing
Correct answer: The internal contact is broken and the relay has failed
A rattling start relay contains a broken internal contact piece, meaning it can no longer engage the compressor start winding and must be replaced.
CAR Troubleshooting & Diagnostics 2
A refrigerator compressor runs continuously but the unit never reaches set temperature.
What is the MOST likely cause?