Furnace not turning on

Questions about repairs and parts for other brands of furnaces and air conditioners. Please note that our speciality is Coleman and Nordyne products, so our knowledge of other brands may be limited.

Moderators: Greg, Mark

Posts: 2
Joined: Sat Oct 13, 2012 9:24 am

Hoping someone can help me out on this. My Thermostat clicks and calls for heat but my furnace doesn't do anything. I tried jumpering to see if I can get any activitiy but I was only able to get the blower to turn on. My pilot is lit, seems all the wiring is in place. The furnace is a Intertherm, older guy Any help is greatly appreciated. Thanks
Posts: 383
Joined: Mon Oct 25, 2010 9:53 pm
Location: Steuben County, NY

First, is the knob on the gas valve set to "pilot," or "on" ?

Posts: 2
Joined: Sat Oct 13, 2012 9:24 am

The knob is in the ON position.
Posts: 622
Joined: Tue Nov 11, 2008 6:12 pm
Location: wisconsin

First, what is the make and model of the furnace and how old is it?

After the thermostate clicks nothing at all happens? No booster blower? Does your furnace have status lights, usually green and either steady or blinking? Is your furnace getting electricity, maybe breaker tripped or something? Just trying to throw out some ideas to check.
Posts: 385
Joined: Wed Apr 07, 2010 10:07 am

Model number really helps. If you have an older pilot model with no booster motor then here's a few things to try. When you have the power on and tstat calling for heat see if you have 24 volts at the control/gas valve. If no voltage then something is bad in the low voltage wiring.

(((QUICK CHECK!! With power off look for any resettable limit switches. Look on left side of blower assembly and below burner intake assembly. Usually a red or brown button right in the middle of them, push it in to reset.)))

If still nothing, kill power, take the red and white wires apart from the thermostat wires at the furnace. Twist red and white wires from the furnace together, this will eliminate the thermostat and wiring to it as a problem. Turn power on, furnace should fire, again if nothing check voltage at the control/gas valve. If voltage is there, turn off power and gas and pull burner assembly. Remove pilot tube and thermocouple, pull oriface from end of burner tube, it's a little brass thingy with a hole in it. Look into oriface to be sure it is clear and then look into burner tube down into the control valve. It should be clear. If you see white in there you need to clean the web out of the tube. Use a Qtip to do this. Put it all back together and give it a try.

If there is no web I would say the control valve is bad and should be replaced.

It would really help to have a model number though as the quick rundown I gave you may not get you going. I have run into some units with limits in tough to reach places if those are bad then you could buy parts you don't need.