Thermostat Wiring

Question 1

The thermostat acts as a __________ between the R terminal and the other terminals.

Answer 1

Switch

Question 2

During heating mode, the furnace thermostat connects the R terminal to…

Answer 2

The *W terminal

Question 3

During fan mode, the thermostat connects the R terminal to…

Answer 3

*G Terminal

Question 4

The color code usually used for 24v thermostat wiring is Red for R, Green for G, Yellow for Y, and ________ for C.

Answer 4

Blue

Question 5

During AC mode, the furnace and AC thermostat connects the R terminal to…

Answer 5

The *Y and *G terminal

Question 6

What happens if you accidentally connect the C wire, which is typically blue, to the B terminal in the thermostat?

Answer 6

The 24v fuse could blow

Question 7

During air conditioning mode, when the heat pump thermostat is set to a lower temperature than it is in the building, the R terminal connects to…

Answer 7

The *Y *G and *O Terminals

Question 8

During heating mode on a heat pump thermostat, when the thermostat is set 1 degree higher than the current temperature in the building, the thermostat connects the R terminal to the…

Answer 8

The *Y *G and *B terminals

Question 9

During heating mode on a heat pump thermostat, when the thermostat is set 3 degrees higher than the current temperature in the building, the thermostat connects the R terminal to the…

Answer 9

The *Y *Aux *G and *B terminals

Question 10

After you turn OFF the power to a 24v thermostat and turn it back ON, there is usually a ___ minute on-delay before it can send a signal to turn on the refrigerant compressor.

Answer 10

Five

Question 11

If the battery operated thermostat starts working intermittently, first replace the…

Answer 11

Batteries

Question 12

On a furnace and ac unit, you can verify that the thermostat is calling for air conditioning to turn on by measuring for 24v at the furnace control board. Put the multimeter probes on the…

Answer 12

The *Y and *C terminals

Question 13

You can verify if the thermostat is calling for the indoor fan to turn on by measuring for 24v at the HVAC unit’s control board. Put the multimeter probes on the…

Answer 13

*G and *C Terminals

Question 14

On a furnace, you can tell that the thermostat is calling for the heat to turn on by measuring for 24v at the furnace control board. Put the multimeter probes on the…

Answer 14

*W and *C

Question 15

If the air handler’s indoor fan continues to run even when the 24v thermostat face is removed, test for 24v at the control board first between the…

Answer 15

*G and *C terminals

Question 16

If a furnace’s indoor fan continues to run even with the 24v thermostat face removed, the problem could be the thermostat wires touching, fan relay contacts stuck closed, ECM Blower module, or…

Answer 16

Safety limit open

Question 17

If the 3 amp 24v fuse blows when the HVAC unit is turned on, even when the thermostat face has been removed, this means that the _____________ are likely touching.

Answer 17

R and C wires

Question 18

On an air conditioning only unit, if the 5 amp 24v fuse only blows when the thermostat calls for air conditioning to turn on, this means that the _____________ is likely touching the C wire.

Answer 18

Y or G wire

Question 19

On a Heat pump, if the 5 amp 24v fuse only blows when the thermostat calls for air conditioning to turn on, this means that the _____________ is likely touching the C wire.

Answer 19

Y O or G wire

Question 20

On a Heat pump, if the 5 amp 24v fuse only blows when the thermostat calls for heat to turn on, this means that the _____________ is likely touching the C wire.

Answer 20

Y B or G wire

Question 21

If all your wires are correct at the thermostat where else do you check?

Answer 21

Check at your control board the wires might not be matched up correctly