Gas Furnace
Re: Blower Motor Not Running
The furnace control board energizes the fan motor through line-voltage outputs for both heating and cooling.
There are two fan speed outputs on the control board: Cool and Heat
- On a call for cooling "Y", the control board should immediately energize the Cool output.
- On a call for heating "W", the control board should energize the Heat output after the burners ignite and the heat chamber has time to warm.
- The control board should also energize the Heat output on a call for Fan-Only "G".
Qty |
Possible Causes (From Most to Least Likely): |
|
Bad Control Board |
|
Bad Capacitor |
|
Bad Blower Motor |
1. Check Furnace Power
- Check for 120VAC at the control board between "Line" and "Neutral".
- You should have to push-in the blower door switch to get power.
- No Power --> Check SSU fuse and breaker
2. Check Low Voltage
- Check for 24VAC at the control board low voltage terminals between "R" and "C".
- No Power = Blown Low Voltage Fuse or Bad Transformer
- Install a jumper wire from "R" to "G" (should energize HEAT fan output).
- Check for 120VAC between HEAT and Neutral.
- No Power = Bad Control Board
- Install a jumper wire from "R" to "Y" (should energize COOL fan output).
- Check for 120VAC between COOL and Neutral.
- No Power = Bad Control Board
3. Check Fan Motor/Capacitor