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Topic: Solution to (Long Term) A/C Problem (Read 531 times) previous topic - next topic
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Solution to (Long Term) A/C Problem

Yahoo Message Number: 35509
At long last we have resolved the problem with the intermittent Dometic heat pump-a/c unit. And this is one to remember.
After replacing every electrical part in the unit and bypassing most of the wiring systems, we replaced the BATHROOM LIGHT and the roof unit has worked consistently for two days.

To make a long story short, one of the two ceiling lights in the bathroom had stopped working nearly two years ago. We purchased a new fixture at a CC rally but never got around to installing it since the remaining light was more than adequate. After brainstorming every possible difference between when the roof unit would work and when it would not, it appeared that it did not work when the bath light was turned on - which is normally most of the time except at night or when parked at our home.

The Thin-Lite fixtures have an electronic inverter ballast. The light which had quit working exhibited burned looking components in the ballast assembly. After unhooking the wiring from this light, the a/c still would not work. Then we found that the light fixture which had continued to work also had scorched components.
We installed the new fixture and blocked off the wires for the second one (until we get another replacement), and miraculously the front a/c-heat pump now works fine.

According to the electrical schematics provided by CC, the bath light wiring is not in the same harness with the front a/c. However, these schematics are likely not "as built" since most of the notes state "typical". It's possible that the root cause was either a short in the 12 v system caused by the defective lights, or perhaps even a stray RF signal emitted by the bad inverter ballasts.

Never give up on a problem!

Jim and Mary Jo Brown
2002 Allure 30778