Air Conditioning Repair Electrical Components and Controls 5

Question 1

A homeowner reports the outdoor unit runs continuously even after the thermostat setpoint is satisfied. Which component is the most likely culprit?

Accepted Answer

Welded or stuck-closed contactor contacts

Answer

Welded contactor contacts keep the compressor and condenser fan energized regardless of the thermostat signal.

Question 2

What does the term 'MFD' (or µF) represent on a capacitor label?

Accepted Answer

Microfarads, a unit of electrical capacitance

Answer

MFD stands for microfarads, the unit measuring a capacitor's ability to store an electrical charge.

Question 3

A technician is checking motor winding insulation integrity. Which test instrument is used, and what minimum reading is acceptable?

Accepted Answer

Megohmmeter; minimum 1 megohm

Answer

A megohmmeter applies high DC voltage to measure insulation resistance; readings below 1 megohm indicate degraded insulation that could lead to winding failure.

Question 4

In a 240V single-phase circuit, what is the voltage measured between either hot leg and the neutral conductor?

Accepted Answer

120V

Answer

A standard residential 240V circuit is center-tapped, providing 120V from each hot leg to the neutral and 240V between the two hot legs.

Question 5

What is the purpose of a ground fault circuit interrupter (GFCI) outlet required near HVAC equipment in some installations?

Accepted Answer

To trip when current imbalance between hot and neutral exceeds ~5 mA, preventing shock

Answer

A GFCI detects small current imbalances caused by current flowing through an unintended path (like a person) and opens the circuit within milliseconds.

Air Conditioning Repair Practice Test

Air Conditioning Repair Practice Test

Air Conditioning Repair Electrical Components and Controls 5