Problem with Furnace

[Viva Las Vegas JDR]

Hi, my furnace started running all the time, blower and propane heat. I can't shut it off with the thermostat. This is what I've tried so far:


1) Replaced igniter control board. I did this since I thought it was the thermal relay (not high temp relay) and my wiring diagram doesn't show the thermal relay anywhere and I could see a relay on the igniter control board. No change.


2) I tried disconnecting all the wires on the thermostat and no change. I could sense voltage on the Furnace wire even when it was disconnected from the thermostat. Even if the fan wires had no voltage on them the blower kept blowing.


I don't know what to try next... any ideas?

JDR

[Will Procter]

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Well, I don't know much. But what I would do first is shut off the propane and elec power source. Then turn them back on, propane first. If it starts up without you doing anything else, you've got a switch problem somewhere.



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[NewellCrazy]

You've already eliminated the thermostat as the culprit, which suggests checklist item #4. Before concentrating on the gas valve, however, I'd perform one more simple test to make sure the thermostat cable isn't shorted. With all power off, remove the wires from the thermostat (there are probably only 2) and use an ohmmeter to check for continuity between the two. If you get any ohmmeter reading (continuity) it suggests those wires are probably shorted somewhere between the thermostat and the gas valve or the circuit board. Good luck

[GORDON HUMMEL]

I'm voting on shorted wires to the thermostat
What is the model of you furnace?

[GORDON HUMMEL]

The above is for my furnaces. Most are similiar
MUST BE A WAY TO ROTATE IT BUT i CAN,T FIND IT?3550

[Viva Las Vegas JDR]

hi, thanks all for your help. I found the problem. It was a poor wiring job. There was a number of wires that are wire-nutted together in different groups. Apparently the two bare wires are the ones that cause it to start. Only guess I can think of is that the vibration of traveling caused them to touch.

3553

[77newell]

Hey Jimmy; good job sussing out the problem and sharing it with us. I for one really appreciate hearing what worked.