Gas and Oil Home Heating Furnaces - Heating issues

Happy Holidays to everyone!

Let me describe the problem I am having with my home furnance.

Lately, usually at night for some reason, my home will be very cold, in the lower 60's. I will notice the air vents are blowing cold air. Brrrrrr

So, I went to the garage and checked the furnace, the pilot light was on, but no burners. Hmmm..strange

I turned heat off from the tstat, then turned it back on, burner lit and it was good to go.

This has happened a few times in the last few weeks.

I replaced the batteries in the tstat (LUX 500) and reset it, still nothing.

Someone at work told me it could be the thermocoupler in the furnace, is this a possibility or does it sound something more major?

The furnace is about 15 yrs old and a Carrier.

That old . Does it have a standing pilot with a good flame on it .Does the furnace have a board that controls it?

Not sure about the board you speak of, but, there is a standing pilot light that is lit and stays lit. It seems like the burners don't light. When it is blowing just the cold air, the burners are not lit, but the pilot is.

To add:

My pilot light is a nice blue color and is about 1 1/2" - 2" in size.

if your pilot is staying lit then the thermocouple is fine, doesnt hurt to clean it up with some sandpaper or wire brush anyway. i imagine this furnace is a natural draft setup and it sounds as if the high temperature limit is opening. causing the gas valve to close and the fan to run continuously until it resets. be sure that all your registers/dampers are open and your air filters are clean.

Thanks for the input.

Yes, the furnace is natural draft. Carrier model 58GP (1982ish).

I happen to run across the manual for this furnace, amazing considering it's 20 yrs old, and I did not know the furnace itself had a filter at the bottom.

I removed the filter, which was pretty dirty, but not horrible, and cleaned it. Hopefully that should solve my problem.

I removed the filter, which was pretty dirty, but not horrible, and cleaned it. Hopefully that should solve my problem.

Put a new one in they dont cost that much. You should put a new one in every 30 to 90 days If it was that bad id also check the blades on the blower wheel and see if they are clean

Will do! I just cleaned the filter as a temporary solution until I can get to Home Depot.

If this does not fix it, could it be this board that was mentioned earlier?

youll have to watch it fire off and take a temperature reading in your supply ducting as well as your return. you'll need a multimeter and some electrical knowledge to be able to single out the board as the problem.