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pjames86 · Mar 10, 2014, 08:31 PM

I have electric forced air heat and it recently started over heating the house. When I have the thermostat set to 70 it will not turn off and I will have to manually turn the thermostat off in order for it to stop. I safely assumed that it had to have been the thermostat, so I replaced it with a new one, keeping all the connections the same and it is still doing the same thing. Does anyone know what could possibly be wrong? Is it possible that this can be the furnace and not the thermostat?

parttime · Mar 11, 2014, 02:15 AM

Hi pjames and welcome, it could be a problem with the wiring between thermostat and the furnace. You'll have a better answer if you post make an model of furnace.

pjames86 · Mar 11, 2014, 07:15 AM

Hey parttime, thanks! It is a Carrier system, model# FA4ANF024000ABAA. The thermostat wiring is in the same configuration as it previously was, nothing has changed, but I will check for continuity through each wire from the thermostat drop to the furnace just to rule out a potential short or open. I did notice however that when I was swapping out the thermostat, that all of the wires weren't previously in the correct location going by the standard color code. I am told that this is common depending on who did the initial install and to just keep them in the same order. Just for my own peace of mind, is there a point of reference that would tell me where the connections are supposed to go on the furnace end so I can make the correction and have all the color coded wires in their correct location.

parttime · Mar 11, 2014, 07:31 AM

Originally Posted by pjames86

is there a point of reference that would tell me where the connections are supposed to go on the furnace end so I can make the correction and have all the color coded wires in their correct location.

Hi pjames, it depends on where the wires are put on the furnace.

pjames86 · Mar 11, 2014, 10:56 AM

OK, so here is where I am at now. I disconnected all the wires from the thermostat but left them connected at the furnace side and checked continuity on all wires (with the circuit break turned off course). What I found is that my orange, red, and blue wires are all electrically the same. I then removed the thermostat wires from the furnace connections(blue connected to brown and red connected to red on furnace), but left them paired with the wires that go to the AC unit and found that only my orange and blue wires were electrically the same and that red was now independent. I do not have a schematic to work off, but does this sound normal or could there be a short.