I have a Carrier Model #4008 048 300AL heater... installed Mid 80's...

Problem is that botht the HEater and A/C operate great.. except if I put the Heater thermostat above 65 degrees.. then it will keep cycling.. the temperature may get above 80 degrees... I can even turn the unit to off.. and it will continue to come on and off. I have replaced the thermostat.. 2 different times.. and same thing happens..

Any suggestions on where to look to fix this issue?

I called a service technician.. and he says on a unit that old... he would only replace it.. won't do any repairs on it...

If I have had or would have any issues with it not working properly.. that's one thing.. but its still a very reliable unit.. :(

You called the wrong repairman to start with. I would not call him a repair man if they cannot repair anything. LOL

This is a very strange operation you describe. I believe your problem might be in the thermostat wiring or a short in the thermostat wiring. If you turn the furnace off by the thermostat it is supposed to be off period.

Remove the red wire off the thermostat and see if it still runs then post back.

I unplugged the red wire and it still comes on... I know its not supposed to be going on... tell that to my unit...

Short in the thermostat wiring OR the wiring for the thermostat is hooked up wrong. You might turn off the breaker to the A/C unit to prevent any damage while you figure this out.

Sounds like you have a heat sequencer stuck. The older style carriers would bring the heat strips on and the heat from the heat strips would bring the blower on using a temp act switch.

So T-Top... where would I find this piece in my unit?



Sounds like you have a heat sequencer stuck. the older style carriers would bring the heat strips on and the heat from the heat strips would bring the blower on using a temp act switch.