: : my gas furnace fan is stuck on with or without the furnace firing up………is there some sort of relay?? is it harry homeowner servicable? : Tony.Depending on the age of the furnace the fix may as simple as hitting the fan control or as difficult as replacing the control board. : . One thing you may want to check is if you have central air,the switch on the thermostat is not in the fanon position. It should be in fan Auto. : A fan control determines when the fan should turn on and off. sometimes they will hang up and not shut off. sometimes you may be able to raise the off setting. : dave.
