Coleman 7655-856
Posted: Wed Feb 02, 2011 1:17 am
Furnace was normal until a few days ago, then it failed to start when the wall thermostat was turned up past room temp. There is no "on/off" switch on the thermostat. I removed the front panel and tapped the on/off switch mounted above the electrical box on the front. That worked a few times, but now the furnace won't light at all. I disconnected the wires to the on/off switch and checked continuity with a voltmeter---switch is working ok. The wires to the on/off switch are hot with 120v. Thinking the problem was the blower motor, I pulled the fan unit off the top of the furnace and put power directly to the motor leads, and it runs fine. Checked the reset switch mounted on the left rear of the blower housing, and its got continuity when the switch is in, no continuity when its out. Problem is the burner isn't lighting when the thermostat is turned up to a demand level. standing pilot light is on and stays on. Checked voltage to the unit at the internal on/off switch and it reads 120. Something is keeping the burner from switching on...any suggestions? Thanks.