Driving home tonight I noticed a clicking sound from under the hood. It turned out to be the tempeture regulator ( the piece that has two solinoids the regulate the hot water going to the heater. Also strange is the recycle air switch didn't work. Parked in my garage for an hour, and the recycle air then worked and the regulator is still cycling on and off every second or so. Anybody had a similar problem or know what to look for.