# Oil furnace won't shut off



## tef (Nov 12, 2007)

I've got oil heat and the furnace won't shut off. The only way I can get it to shut off is to turn off the main shutoff switch on the side of the furnace. Turning the wall thermostat to "off" doesn't work. Removing the digital thermostat from the wall doesn't work. I also tried unhooking one of the wires on the relay on the furnace that I believe brings the signal in from the thermostat and when I turned power back on the furnace fired right back up. I've tried to make sense of the wiring diagram posted on the furnace, but I'm a little over my head. The only thing I can figure is that the relay has a short in it. Can anyone help?


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## skymaster (Jun 6, 2007)

check the terminals on the control unit that the thermostat wires go into, look for something that could be shorting out, if you cant find anything visible anywhere get a tech in there ASAP.
If may be the control unit failed but normally they fail in the OFF position.
This could be nasty so dont play with it, get help.


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## tef (Nov 12, 2007)

*Control unit was the problem*

I called the service tech and it was indeed a bad controller. For those who may not know anything about oile furnaces, the controller in this case was a box on the furnace blower with a red reset button and two wires in from the thermostat and two (yellow) wires in from the cad eye sensor. The tech removed the cover of the controller and got a relay or something to get unstuck and then things worked fine. He replaced the controller. Not sure yet what the 40 minute visit cost me.


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## skymaster (Jun 6, 2007)

I luv it when I am right once in my lifetime:laughing: Glad it is fixed:yes:


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