Date:         Sun, 30 Jun 2019 10:36:03 -0700
Reply-To:     Alistair Bell <albell@SHAW.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <albell@SHAW.CA>
Subject:      Some dometic notes
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Hi,

Last weekend a friend dropped off a dometic to see if I could get it to work. He couldn’t get it lit, he had cleaned the chamber and jet.

I found right away that the gas line to the jet was not firmly tightened. I tightened that and I got it lit right away.

The exhaust flue warmed up, and I waited, waited, but no cooling. And, this is important, no heat coming off any of the piping on the back. Especially notable that pipe not getting warm right by the cooling fan thermoswitch.

Over the next few days I inverted the fridge a few times. Maybe there was a chromate crystal block, ha.

No luck. But I could hear liquid in the system so I assumed the system was intact, no lost ammonia/hydrogen.

Then I tried AC function. Fridge cooled down, and the pipes on back warmed up as expected. 

At that point I decided to have a look at the chamber work that had been done. I cleaned the jet in vinegar, in my ultrasonic cleaner. Came out shiny and jet clear. Then I noted that the thermocouple probe in the chamber was severely eroded. I replaced it with a better looking spare and buttoned everything up.

Fridge lit, and the flame noise at the exhaust was more pronounced. I had wondered about that before when I first got this fridge, seemed to be not as loud as my fridge.

And yes, the fridge cooled down and the pipes on back warmed up as they should.

It almost seemed, thinking back on it, that initially the flame was on “pilot mode”. There was flame, but not enough to get the system working.

I don’t know if the thermocouple erosion was the culprit. I woudl have thought that if that probe was kaput then the fridge would not even burn at a pilot setting. I thought the probe signal, low voltage to the shut off valve, was more or less binary in effect.

But maybe not. In any case what I did made the fridge work. Oh and the burner jet did appear clear before I cleaned it. But maybe it was not completely clear and my cleaning just did the trick. Don’t know.

Anyway, friend happy it’s working. And I’m glad it’s out of the barn.

Alistair