Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

What voltage is found from terminal Y to the input side of the coil on line #11?

1. 24 volts

2. 0 volts

3. 120 volts

4. 240 volts

The correct answer is: 0 volts

In the context of HVAC systems, when measuring voltage from terminal Y (which typically connects to the cooling system's contactor) to the input side of the coil on line #11 (often associated with a relay or contactor in the control circuit), a reading of 0 volts would indicate that there is no voltage present at that specific measurement point while the system is inactive or the thermostat is not calling for cooling. When the thermostat is not demanding cooling, the Y terminal will not have voltage applied to it, meaning the input side of the coil on line #11 also won't be energized. Therefore, a reading of 0 volts is expected. This outcome can signify that the control circuit is open, and no action is being taken by the compressor or the fan motor since there isn’t an active call for cooling. It illustrates that the electrical path is not complete or that there is no power being supplied at that moment from the cooling circuit. Thus, a measurement of 0 volts reflects the expected state of the control circuit when it isn’t demanding operation.