It was the high temp limit switch, and it was tripping at about 110 degrees instead of 180. It kept short cycling, and the house got down to 58F. Brrrrr It to

It was the high temp limit switch, and it was tripping at about 110 degrees instead of 180. It kept short cycling, and the house got down to 58F. Brrrrr It took an extended run to get the house back up to temperature, but it had no problem with a correctly functioning switch.