[stanleyz]

OK, I'm going to post this as a close out on this thread. This will be long but if you are experiencing similar problems to mine it will be worth your time. First let me say I did not repair this unit so much as I pestered it in to submission. Here is the sequence of events.

1. Over a year ago my bed room air conditioner started running away and could only be stopped with the circuit breaker.

2. Problem was the control card in Zone 2 air conditioner so I replaced it. That corrected the problem.

3, In Feb, that unit began failing if left on Cool fan high or on cool fan auto with a temp spread of 9 degrees or more. It would run for a short time and then the fan would stop and the compressor would hum. On cool fan low or auto with a temp spread of 8 or less it would run and cool all day.

4. I replaced both capacitors but nothing changed. When I got home I removed the fan motor and found some black winding and some burnt paper. A knowledgeable electric motor guy looked and said it was toast.

5. I replaced the motor. That is a real chore. I wouldn't do it again. Anyway with the new motor the unit continued to fail on fan high cool setting but run forever on cool fan low.

6. I floundered around working on it off and on and reading a lot of forums but I had no clue. Checked amps and it was pulling like 22 amps. Too high. Checked the temp of the fan motor and it was really hot, like 170 degrees just before it stopped. That was a major clue. I then knew what was happening: motor was getting too hot and seizing or being stopped by an internal heat sensor. Now what was causing it.

7. On another forum a guy mentioned that he had the same symptoms and it took two techs 4 hours each and they couldn't figure it out. The final answer came from Dometic that some wire had to be cut but he didn't know which one,

8. I was about to remove the control board from my good unit to install in the bad unit when I pulled on the yellow wire that says medium speed on my chart. It was loose with a cap on the end. Holycrap. I went to the problem unit and dis connected the yellow wire and from then on it is running like a new one. That was it, the yellow wire was causing the fan motor to over heat on cool fan high.