Air Conditioning Repair Electrical Systems and Controls 3

Question 1

A hard start kit (potential relay and start capacitor) is added to a compressor. What is the primary purpose of this kit?

Accepted Answer

Increase starting torque to overcome high head pressure

Answer

A hard start kit boosts starting torque, allowing the compressor to start against elevated head pressure or under low-voltage conditions.

Question 2

On a heat pump system, the reversing valve solenoid is energized in cooling mode. If the solenoid coil reads infinite resistance, what will happen?

Accepted Answer

The system will operate in heating mode only

Answer

An open reversing valve solenoid coil means the valve cannot be electrically shifted, leaving it in its de-energized (heating) position.

Question 3

What is the purpose of a time-delay relay (TDR) installed in an air conditioning control circuit?

Accepted Answer

Prevent short cycling of the compressor by enforcing a minimum off time

Answer

A time-delay relay enforces a minimum off period between compressor cycles to protect against refrigerant pressure equalization issues and motor overheating.

Question 4

A technician uses a megohmmeter to test a compressor motor winding to ground. A reading of 2 megohms is obtained. What does this indicate?

Accepted Answer

Moisture or degraded insulation is present

Answer

A compressor winding-to-ground reading below 1,000 megohms suggests compromised insulation, likely from moisture ingress or winding breakdown.

Question 5

Which safety control opens the circuit to the compressor contactor coil when refrigerant pressure exceeds the set point?

Accepted Answer

High-pressure switch

Answer

The high-pressure switch is a normally closed safety device that opens to cut power to the contactor coil when discharge pressure exceeds its cut-out setting.

Air Conditioning Repair Practice Test

Air Conditioning Repair Practice Test

Air Conditioning Repair Electrical Systems and Controls 3