I cannot find the "name" of my furnace, but it is a Carrier CK5BXWO48024AAAA. It is gas. We bought the house (built in 2001) from someone who didn't provide a manual.

Early Dec, the blower is running nearly constantly, but the temp never gets above 66. So, I went down there, and it is flashing 33. I read the codes and the easiest fix is to try changing the filter (which hasn't been replaced in forever, I know you're cringing, but I just had a baby, and my husband is super-not-handy). That worked.

One month later, the same problem. I changed the filter again, thinking maybe the filters we bought are very inefficient, plus we got the carpets cleaned after the cat died, blah, blah.

Two weeks after that, it is not heating the house properly again (though the light didn't blink this time). Changed the filter and thinking I should try some of the other solutions, but I don't know how to "manually reset" a "flame roll out switch."

Could someone walk me through a couple of simple things to try (I catch on quickly, but know little about furnaces), or should I call in a serviceman?

Thanks!

The "CK" number you provided is from a cased air conditioning coil, not the furnace model number. Locate the label inside the furnace, on the sidewall, and post model # - probably starts with "58". If the unit is malfunctioning AND power supply has not been lost, the status LED should be flashing to display a fault code. Without this information, ability to help you over the 'net is very limited, unfortunately.

Okay, sorry. Is "58PAV135-20" more like it? It was manufactured in 2001.

That's it. No LED's flashing? Is the house warm?

Here is the service manual for series 131. I don't know if that's your series.

To answer KC13: no LEDs right now, and the house is warm for now, but I can't keep changing the filter every 2-4 weeks. The LED flashed 33 the first two times we had the problem.

Thanks for the manual K.I.S.S.