The 5 amp fuse on my control board blows as soon as you ask for heat. With a good fuse in the AC work fine and you can switch the fan from Auto to Fan on with no problem.
As soon as you request heat the fuse blows and when I try to run the fan to on nothing happens.
I read on-line to jump the W and R on the control board and see if the fuse would blow or if the heater would kick on so I did that. The exhaust motor kicked on then the gas ignited and after a few minutes so did the fan and I had heat.
I assumed it was the low voltage wiring from the wall t-stat to the control board so I got new wire and ran up to the attic. I even installed a new t-stat. Exact same problem. AC works fine but as soon a I switch to heat the fuse blows. Any help would be appreciated.
Best Answer
On the furnace control board again jumper the red to the white. Everything OK? Now, on the new stat wire, disconnect the Stat completely. Now at the stat location twist together the red and the white. Does the fuse now hold. The furnace should start. If this is the case, you are doing something wrong when you are connecting the stat. Happy hunting and Good Luck.