I have a Trane XR90 furnace. The IFC board went out 2 winters ago. It was replaced along with the ignitor electrode. It has worked fine until 2 days ago. I turned my heat on 3 days ago and everything worked fine again. The next day it blew the 5 amp fuse on the IFC board. I replaced the fuse today and it worked for about 20 minutes. Then it blew the fuse again. I've checked the wiring to the thermostat and the IFC board. Does anyone have any input on what this problem could be? Much appreciated.
Disconnect all of the wires from the furnace that come from the thermostat. Then use a jumper from R to W on the IFC board, and leave the heat run. If it doesn't blow the fuse in 30 minutes. then something is wrong with either the wires, or the thermostat, if it has more then 2 wires to it..
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