My furnace has the red light blinking rapidly without a pause. The manual says to: Check for correct line voltage polarity. If units are twinned, check for proper low-voltage (24v) transformer phasing.
Any idea's what this means, where do I start. It has been in service for 9 years trouble free, how would the polarity change? Any help would be greatly appreciated.
I was trying to trouble shoot it last night and found that there was no voltage coming out of the board to the pressure sensor. When I went to the service department to purchase a new board they said did I check my transformer power output? I don't get any power on the volt meter, but if I disconnect it from my board the furnace fan will not run. Plug it back into the board and the fan will work. The board is $284.00 plus tax so I don't want to purchase it if that is not the problem.