Thermostat will not shut down furnace when switched to "off" position, but will shut down when set temperature is met.

What model do you have?

Honeywell RTH2300/RTH221

Just to get started this may help RTH2300B I did not recall that you can shut this stat to an OFF position, can you?

Yes. On the bottom left side of the thermostat there is a "Heat", "Off" and "Cool" position where you can slide the switch. On the bottom right side there is a switch you can slide the fan to "Auto" or "On".

Also the link you posted is the correct thermostat. The picture on that page is the same thermostat that I have. If you look at the bottom right and left of the picture of the thermostat you will see the print of what I was trying to explain on the above post.

Well, I guess we can forget all I wrote above. I woke up this morning and only my blower motor was running on the furnace as well as my condenser outside. I shut off everything. Shut off breaker to condensing unit and unhooked my 2 wires from the furnace board that controls the contactor on the condenser. Tried to restart the furnace, but the vent motor comes on for about 3 seconds and shuts down. After a couple more seconds the blower motor comes on. Any help?

I am stumped, maybe time to make a call, sorry

Is this a new stat? If so, are you sure it is wired correctly. Let me know if its new, or has been in use and worked correctly before. Also, I need to know if you have a heat pump system, or just conventional forced hot air gas furnace with central air conditioning. Just a heads up, if it's a heat pump, Im afraid I will be of no real use to you. If it's a conventional system, depending on the brand and year, I may be able to at least point you in the right direction. Or, as ballengerb suggested, make a call to a local tech and they should be able to get you fixed right up. Please do let us know either way.

I found out the problem! I did some voltage testing on the vent motor as well as the transformer. Then I went to the control board of my furnace and checked the voltage from Red to White as well as Common to Red. I had 24v from R to W, but not C to R. So I took the face off the base of the thermostat and found that a battery had exploded inside. Not sure if something caused this or if the battery was just garbage. Needless to say I went and bought a new thermostat and now have heat! Thank you very much for taking the time out of your day to help!

Hey, just glad you got it fixed. Good job, and thanks for the update.