Was getting pretty cool in the house and the thermostat was reading 64 degF ambient, was set at 68 on heat. The tstat was switching on/off ok, I could hear it when I switched from heat to off, back to heat. With heat switch on, went down to the furnace to discover a rather loud electrical humming noise. This is new.
I took the top cover off to try to eyeball the source of the noise and seemed like it was coming from the exhaust fan, the first component actuated in the path of electrons flowing from the control board, so it seems.
So pondering this I flipped the emergency switch a couple of times over the course of a few minutes. The last time switching on the fan kicked in and the heat is blowing for now.
Question, would it be a relay sticking that controls the exhaust fan or the exhaust fan motor? The loud hum sounds like a stuck motor. It's a Rheem 80+ 5 ton unit and is almost five years old.
Thanks for any insight, Matt