Air Conditioning Repair Electrical Components and Controls 3

Question 1

What is the primary function of a crankcase heater on a compressor?

Accepted Answer

To prevent refrigerant migration and oil dilution during the off cycle

Answer

Crankcase heaters keep the compressor oil warm so refrigerant does not migrate into the crankcase and dilute the lubricant during shutdown.

Question 2

A time-delay relay in an AC control circuit is set for 5 minutes. What is its purpose?

Accepted Answer

To prevent short-cycle compressor restarts

Answer

Time-delay relays prevent short cycling by enforcing a minimum off time before the compressor can restart, protecting it from pressure equalization issues.

Question 3

When testing a capacitor with a capacitance meter, a reading of zero indicates what condition?

Accepted Answer

The capacitor is open (internally broken)

Answer

A zero capacitance reading means the internal element is open and the capacitor cannot store a charge.

Question 4

A compressor is wired to a 208/230V disconnect. Which wire gauge is required for a 30-amp circuit per NEC?

Accepted Answer

10 AWG

Answer

NEC requires 10 AWG copper conductors for a 30-amp circuit at standard ambient temperatures.

Question 5

What type of transformer is typically used to supply 24V control voltage in a residential split system?

Accepted Answer

Step-down transformer

Answer

A step-down transformer reduces line voltage (120V or 240V primary) to 24V AC for the low-voltage control circuit.

Air Conditioning Repair Practice Test

Air Conditioning Repair Practice Test

Air Conditioning Repair Electrical Components and Controls 3