Hello. I woke up this morning and noticed my indoor blower is running even though its off (no ac/heat/fan auto). I cut the power and opened the air handler up to do a quick inspection and didn't see anything wrong. I cut the power back on and while the blower didn't come on, the circuit board started to smoke. It's a fairly simple unit (so I thought) with little wires in it, so I disconnected everything except for the main plug going to the board. Turn the power back on and it starts to smoke again. Now I'm thinking there must be a short. I couldn't find anything upon visually inspecting it, so what would be some good tests to run?

Replace

Your furnace should know,, smoking is bad

Replacing my furnace seems a little extreme.

The circuit board,, is that not what you said was smoking?

Yea sorry wasn't 100% sure what you meant. I have a spare board that I quickly tried out. Although it isn't brand new, it was taken off another unit I had a while back. This one started to smoke and actually left a burnt mark on it. Unfortunately I didn't cut it off in time.

I was hoping of doing some tests with my multimeter but, I just need to know what I should check for.