Furnace Fan Not Working On Auto

My furnace fan blower will not work when set to the auto position.

Furnace fan not working on auto.

A furnace requires proper gas flow to the burner assembly as well as electricity to the thermostat to actuate the heater. Next you will turn your thermostat to the fan only mode. There are a couple of ways to do this depending on your thermostat but the. You can check to make sure it is not the thermostat by taking the green wire off the thermostat connection or taking it loose from the furnace s control board.

I could hear the relays clicking occasionally so i investigated a little and found the elements are heating up and cycling the relay inside the thermostat cycles not repeatedly just when you turn it on and off but the fan blower doesn t run. A shorted thermostat wire can cause this too but it is very uncommon. Just cool air blows. Usually when you set your thermostat to auto or automatic the burner will ignite when the temperature falls below the temperature you set on the thermostat.

There are several causes for the heater not activating and you can troubleshoot the problem yourself before calling in a. Intertherm electric furnace blower works in on not in auto i came home from work last night turned the heat on and it didn t work as advertised. A control board relay where the relay contacts are welded shut can cause the blower to run continuously too. When i do turn the fan to the on position no hot air is blowing out of the vent.

For this case or if your blower fan or furnace fan won t start at all see. What happens when the burner won t ignite and the fan won t blow warm air into your house. Replace the fan limit controller. This is a bad temperature sensor in the unit.

After ruling out all of the simple problems above the most likely cause of a furnace not blowing air is a problem with the blower fan itself which if you remember is the fan that circulates your house s air over the heated coils. In auto mode the furnace will heat up but the fan won t run the heater then reaches the hi limit and the system shuts down the fan never runs. I replaced the thermostat and get the same results.