I think my model is a 641 if this helps. The fridge is not cooling all of a sudden. Everything fine as recently as this morning. The freezer is still frozen but this may be because it only quit cooling today. No problems with indicator lights on eyebrow panel. Will light on propane or run on electric. The burner tube is hot when I touch it outside, however the cooling unit tubing is not even warm where it is usually hot. Is there anything this could be besides a bad cooling unit?