313D Electrical Schematics and Controls 3

Question 1

What is the function of a hard start kit (potential relay and start capacitor) shown in a schematic?

Accepted Answer

To boost starting torque and reduce locked-rotor amperage duration

Answer

To provide surge protection during lightning storms

Answer

To soft-start the condenser fan motor

Answer

To regulate refrigerant pressure during startup

Question 2

In a schematic, what does a contactor coil symbol (circle with a letter designation) energize?

Accepted Answer

The main power contacts that supply line voltage to the compressor and condenser fan

Answer

Only the run capacitor circuit

Answer

The 24V transformer primary winding

Answer

The crankcase heater element

Question 3

A low-pressure switch in an AC schematic is wired in series with the control circuit primarily to:

Accepted Answer

Shut down the unit if refrigerant loss causes suction pressure to drop below safe limits

Answer

Protect against high discharge pressure

Answer

Cycle the condenser fan at low ambient temperatures

Answer

Prevent the blower from operating without refrigerant flow

Question 4

On a residential split-system schematic, which wire color is most commonly used for the 24V 'Y' (cooling) signal from thermostat to air handler?

Accepted Answer

Yellow

Answer

Red

Answer

White

Answer

Green

Question 5

What does a ground fault circuit interrupter (GFCI) monitor in an electrical circuit?

Accepted Answer

The difference in current between the hot and neutral conductors

Answer

The total current draw of the connected load

Answer

The voltage level on the hot conductor only

Answer

The insulation resistance of the equipment grounding conductor

Question 6

Which type of diagram shows the physical location of components and the actual wire routing between them?

Accepted Answer

Wiring diagram

Answer

Ladder diagram

Answer

Schematic diagram

Answer

Block diagram

Question 7

In AC system controls, what is the role of a defrost control board in a heat pump schematic?

Accepted Answer

It initiates and terminates the defrost cycle to clear frost from the outdoor coil

Answer

It regulates indoor humidity levels during cooling

Answer

It prevents the reversing valve from switching during heating

Answer

It controls the variable-speed blower motor speed