Furnace will not stop running

[moundtown]

I have an old Intertherm electric furnace model: MAC 2454A. It will not stop running. Two years ago the heating element would turn off but the fan kept running at which time I installed a new sequencer and that fixed the problem. Now neither the heater element nor the fan will stop running. I have disconnected the thermostat which made no difference. Any ideas to what might be causing this? Thanks

[mastertech]

furnace not cycling or turning off

That's not a good problem and I imagine it gets a little warm. You stated the system was an inertherm and electric furnace. Well being electric the sequence of operation is upon the demand for a heat call,there will be a small time delay and the blower will come on with the first heating element. Now it depends on the size of your furnace, 15 kw 20 kw and so forth will bring each element on. After the home has heated up and cycled off the thermostat, the last element that came on will be the first element to shut-off. This sequence will continue until the system shuts down completely. It sounds like the sequencer has hung up on you again not cycling the fist element and blower off. You can tap the control and that might shut it off, the better and more safer way is to kill the power to the system and change out the sequencer. Get the right style to make sure the fan and each individual heating element comes on and off in the proper sequence. Those are called a "stack switch" and is sized by the number of heating elements is in your furnace. Hope this helps out! There might be one other thing that the low voltage tstat wires may be shorted out and if that's the case remove the stat wires at the furnace and if it shuts off than theres your answer if not and keeps running than the sequencers are your answer!

[Jim-Martin]

Heres the answer

1. Pull the thermostat wires off the terminal board at the furnace.

If that doesn't solve the problem, you probably have a low voltage short somewhere in the wiring. You'll need to use a meter to hunt down the short.

[dfitz3390]

hmmmmm i think thats what the previous person advised Jim

[Jim-Martin]

Sorry. I didn't read the previous post.