rwilliamsr42

Now that you mention it that makes sense. I also thought that the relay might just be to weak to complete the switch over. But I do not know of a way to test for that. I assumed that it was either good or bad.

To all who responded to this thread I thank you. Today I spent some time of the roof of my coach cleaning and checking both AC's. The rear which was the one that was only blowing hot air got my attention. I removed the shroud and everything looked to be in good shape. I used a small leaf blower and cleaned some of the debris, leaves, some acorns and gypsy moths and then tested the solenoid and it was OK. I then used the technique that was recommended by my mobile RV repairman. I had my wife turn on the A/C while I used the handle of my screw driver to beat on the reversing valve. That worked, the unit is working well without any other problems. Apparently the sticking reversing valve issue is a well know problem with this Duo-Therm Heatpump A/C. I hope my experience will help others should they have the same problem.

Thanks for the tip. I hope to continue with my diagnostic odyssey next week. Currently in Northern Michigan the temp is 51 so go heat pump.

Thanks for the suggestion Gary. I down loaded an older Duo Therm shop manual/installation and trouble guide and I have been looking through the problem list and their solutions. Not really enjoyable reading, but there are a few good tips in it.

The rear AC/heat pump in my '02 Diplomat is blowing hot air only. Due to covid lock downs by the Commissar here in Michigan it has been more that a year since I have used the coach. I have read a lot about problems with reversing valve becoming stuck and failing to switch from the default heating to cold air. I am parked for season and contacted a mobil RV repairman who basically admitted he wasn't knowledgeable with heat pumps. I appreciate his honesty and saving me the expense of a service call. He did say he had talked with a Duo Therm tech who admitted that the problem was either a bad solenoid which was repairable, or a stuck faulty reverse valve. If the solenoid was good, he advised to just bang repeatedly on the valve to possibly free-up the stuck valve. If that did not solve the problem the only alternative is a replacement. I would like to hear what experiences others have had with their Duo Therm heatpumps, and what are your thoughts about a defective reversing valve causing a complete replacement of the heat pump.