Heat fan won't come on in auto will work in manual on fan stays on all the time it does cut heat on and off with thermostat
mygirlsdad77
Dec 20, 2011, 06:18 PM
Sounds like you need a new control board. The fan relay for auto heat fan operation is built into the control board and cannot be changed out separately. I know, it sucks, but when this occurs, its time for a new control board.