Can use any help...
Have an older Carrier Gas Furnace that has gone on the blink. The hall thermostat just stopped working, but only on the HEAT side. (Run the AC just fine.) Was told it was the "thermocupler", so we replaced that, but nothing happened. What else could be wrong? Or should I just call in the professionals! Again any help will HELP!! I am at a lost.
Thanks in advance. The model # is 58BB120. I have no manual.

Did you relight the pilot?

Is the pilot flame touching 1/2 of the thermocouple?

We had to relight the pilot and at first it didn't want to stay on, but once the thermocouple got warm it did. I would say that it is in the flame about half way.

Is the main lever on the gas valve turned to ON instead of pilot?

Many people relite the thermocouple and forget to turn the gas valve to operate or ON.

If the above is not the problem make sure you have 120 volts after the furnace disconnect switch. If you do then continue on the see if you have 24 volts at the transformer.

The pilot light is on. The thermocouple is in the flame. Where would I locate the furnace disconnect switch? And while your at it... where would the transformer be located? Would I test these with an OHM meter or something else?

A volt ohm meter will work.
If you cannot find the on and off switch on the furnace and you do not know what a 24 volt transformer is I am not going to give further instructions because in my opinion you do not need to be working on any gas or electric device.

You can get hurt or killed and I will not be a part of that. Your expertise in electric is what I am afraid of. Best for you to call a professional before you get hurt. Sorry.

Thanks for your help that you did offer. I understand the whole thing about it being gas and electricity etc.! I just thought that if it was as easy as replacing a plug or checking wire connections and save myself the expense of a service call for a minor thing. It seems to be more complicated than that. I will tell my husband what you suggested and go from there. We will probably call in the professionals! Thanks again for all your help! Have a nice night.