:mad: I have a furnance/air conditioner and the thing keeps running and running. I added a new theromast to it. Still did not fit the problem. I have to manually go down and turn it on and off. It will not shut off.

It says to look for the relay switch, but don't know where it is, they say on the furnace, it may be just be turned to the on position. Don't know, can't find it. Anyone have this problem?

Explain what you mean by "keeps running and running" does that mean that you turn the thermostat off and it continues to run. Tell a little more about what you have to do to make it stop running,

If this is an older model furnace, the fan/limit switch may have an auto/on switch. Look for a siver box about the size of a playing card inside the furnace compartment up high...