I have a Trane xe80 furnace. I hear a small hum from the control board when the furnace is not running. Is this normal? The red light blinks as usual.

There are some small relays on the control board which might possibly hum a tiny, tiny bit, but I would lean towards the 24 volt transformer as being the hummer. Unless it is fairly loud (or quite hot), a slight hum for a transformer is normal.

Hope this helps,
WallyH

OK, thanks