313D Electrical Schematics and Controls 4

Question 1

What is the purpose of a transformer in the residential AC control circuit?

Accepted Answer

To step down 240V line voltage to 24V for the low-voltage control circuit

Answer

To step up 24V to 240V for the compressor

Answer

To regulate current flow to the condenser fan motor

Answer

To convert AC power to DC for the control board

Question 2

A run capacitor shown in a schematic is connected in series with which motor winding?

Accepted Answer

Start winding (auxiliary winding)

Answer

Main run winding

Answer

Both windings simultaneously

Answer

Neither winding — it is connected across the power supply

Question 3

When reading a pictorial wiring diagram, a wire shown going to a splice or junction with a dot indicates:

Accepted Answer

An electrical connection between crossing or meeting wires

Answer

An open circuit at that point

Answer

A wire that continues to the next component without making connection

Answer

A test point for measuring voltage

Question 4

In a residential AC system, the 'G' terminal on the thermostat controls:

Accepted Answer

The indoor blower fan relay

Answer

The reversing valve solenoid

Answer

The ground fault protection circuit

Answer

The compressor contactor coil

Question 5

What does a solid triangle or arrow symbol on a schematic pointing into a wire or component indicate?

Accepted Answer

Direction of conventional current flow or signal direction

Answer

A fused disconnect point

Answer

A mechanical interlock

Answer

An adjustable component

Question 6

A crankcase heater shown in an AC schematic is typically wired to be:

Accepted Answer

Energized continuously when the unit is powered off to keep refrigerant from migrating into the compressor oil

Answer

Energized only during compressor operation

Answer

De-energized whenever the unit is powered

Answer

Controlled by the outdoor ambient thermostat only

Question 7

In troubleshooting with a schematic, if voltage is present on both sides of a normally closed safety switch, what does this indicate?

Accepted Answer

The switch has opened (tripped) and is blocking current flow to the load

Answer

The switch is functioning normally and the circuit is complete

Answer

The switch is welded closed and cannot open

Answer

The switch is bypassed by a parallel circuit