Originally Posted by Toddupton
Unscrew the red wire and touch it to the little brass piece in the end of the yellow wire and hold it there and see if it comes on. It might take a few seconds for something to happen. Did you kill all 12 volt power to it for 30 seconds and turn it back on. The unit will lock out if it does not lite.
That won't eliminate the thermostat... just the on/off switch.
Unscrew the red wire and touch to the white wire. (lower left)
If the furnace blower starts to run, the thermostat is bad.
If the red wire isn't long enough to pull down and touch the white wire, get a short piece of wire and use as a jumper between those two wires.