[Richard]

I finally got around to installing the data acq software to see what the AH was doing. The photocell was acting all squirrely during the run cycle. Lot's of erratic voltages. So I thought bad or loose connection. Soldered the crimped connections at the photocell, covered them with shrink fit and it seems to be fine.

But this is still a horses, not zebras thread. When firing up the AH during the test runs, I had tug boat quality black smoke. That usually indicates partially burned fuel, or not enough air. Did the usual of checking the seating of the Webasto, changed the nozzle, and checked all the rubber grommets at the wire and fuel penetrations. No dice. Still black smoke. I was about to tear into the unit, all the time telling myself, think horses not zebras. Duh huh. During all the fiddling with the Webasto, the air shutter on the bottom of the unit had moved into an almost closed position. Opened the air shutter and the black smoke magically disappeared.