Furnace will not shut off

[jeffmatthews]

I have a problem and i hope someone can help me with. I have about a 5 year old carrier furnace gas forced air. I also have a programmable thermostat and it doesn't want to shut off sometimes. I have to manual shut it down and start it back up when it gets cold in house. As you can read from profile i live in upstate ny and it is cold out. So when i leave my thermostat on , it stays running until i manual shut it down. This doesn't happen all the time. SOmetimes it is fine and works for a week or so. The batteries are brand new. When i unhook the wires that are connected to thermostat it also shuts down. So i think it might be thermostat.. Any ideas ?? Please help if you can thank you JEFF

[imeduc]

When i unhook the wires that are connected to thermostat it also shuts down. So i think it might be thermostat.

If like you say you can pull the R wire off the tstat and it shuts down I say get a new tstat.

ED

My mistakes dont define me they inform me.

[Mike3]

Sounds like you have nailed it. As long as you are sure t'stat is up to temp. Also you might want to check for cool air coming out of wall behind t'stat where wires come thru. If cool air plug opening.