Resurrecting this thread from the dead:
I just purchased an 06 Essex (eplex) and only had one HVAC unit (zone 4) working when I got it. 90 deg sunny day here at Daytona Speedway and it was getting unbearable. I had purchased the 5 button controller after reading the thread linked above and had been meaning to try it as a means of troubleshooting since two of my room thermometers were reading 50deg or more off (one is pegged at zero). I wasn’t sure what the issue was but fans wouldn’t run nor would any other mode work in zones 1 and 2.
I plugged RJ cable above the driver into the 5 button controller and got code EE, which from another thread I found I needed to hold the mode and zone buttons while turning the controller on. Then boom I was able to get all 3 zones working properly for the first time.
Which still begs the question as to why they weren’t working on eplex. I suspect the 2 room thermometers that are reading incorrectly could have something to do with it? But even the fans wouldn’t run before which I think have nothing to do with thermometers. Possibly need to repair the RJ connectors at the roof units themselves? If so not sure why the 5 button allows them to work properly thru the same RJ connection.
It does seem like the temperature is now controlled by the 5 button. I had it in the upper cabinet above the driver and it was quite warm up there. The ac stayed on well below the set point. When I moved the 5 button out of the cabinet into the room air, all 3 ac shut off within a few minutes. So it seems like the 5 button controller is also acting as a single room thermometer for all 3 HVAC zones. Which is better than nothing but doesn’t really “zone” the coach anymore if you wanted the bedroom colder than the living area, for example.
Or is all this simply the sign of an eplex system on its way out? All other functions seem to work great. Do I neeed to just get new room thermostats for eplex or is it the RJ connectors on the roof or both?
Anyway, huge thanks to whoever figured this out!