Goodman Furnace Won't Shut Off

anonymous

I have a Goodman GMP 075. It's approx. 10 years old. 6 weeks ago it wouldn't come on and cycle properly so it was cleaned and we had the ignitor and blower replaced. It worked fine until yesterday. Now it won't shut off unless I trip the switch. The thermostat is new. Any comments?

NickTech

Check the wiring in the furnace at the low voltage terminal connections.
Check the wiring to the thermostat, make sure the color codes correspond to the color codes at the furnace (R red = 24v supply into t-stat, and W white is 24v out to the heating circuit.)To diagnose simple disconnect one of the 2 heating wire (R or W) and unit should cycle off. If not, the problem would be found in the furnace wiring. If it is a round T87F type t-stat, make sure the red shipping plug is removed. Good luck!
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