E1 Error Message on Dometic A/C Unit on 2019 Serenity 23CB

[ISWANDERLUST]

Hi Folks,

Hoping for some feedback from you all. We bought our new AS in July of last year from RV One near Orlando, Florida and are getting an E1 message on the Dometic A/C. Here are the facts:

- A/C turns on and within a minute we get the E1 message but not all the time (the issue began happening in April).
- We followed the instructions in the Dometic manual and reset the unit. This did not work.
- After some research online we did a hard reset where we took the thermostat off the wall and unplugged the cord (looks like a phone jack). There was no condensation on the panel; it was dry. This worked as long as we don't put the thermostat back on the wall. In other words, the thermostat is connected but hanging from the wall.
- If we place thermostat on wall E1 message comes back on.
- This happens whether trailer is plugged into the house with adapter or plugged into 30 amp. We know this because we camped in April with full hookup and issue persisted.
- Called JC and went over what I just explained. They sent us a new thermostat thinking it was a bad thermostat but issue persisted.
- Called JC and they authorized us to take it in to a Dometic authorized trailer repair shop in Miami. They reset it and it worked but did not investigate as to why this happened because they got it to work. They said AS would not reimburse them or us to "find the problem" when they already got it to work.
- Had plugged in A/C at home several times over the last 2 weeks and it worked with no problem (plugged into the wall). Nothing else besides lights were on.
- Today we got the E1 message when my son turned on the unit. I should note that the refrigerator is also on (using electricity not gas) because we are preparing to leave on a trip.
- We tested the voltage on an outlet and are barely at 120.

Any suggestions or insight would be appreciated.

Maite

[wulfraat]

This is likely related to the 4-pin "telephone" cable that runs from the main thermostat up the to control module on the AC on the roof.

Because this is intermittent, and because the main thermostat has already been replaced, its likely that there is dust / dirt on the female connector up on the roof, causing a connectivity issue with the thermostat.

It's also possible that the 4-wire plug is not fully inserted in the female connector on the control board on the roof unit.

Finally, worst case, the cable itself may have been damaged somewhere along the way between the thermostat and roof unit, inside the walls or what have you. It could be tightly pinched and there may be a broken wire inside the cable that is making intermittent contact.

I'd fist start by getting up on the roof, remove the white ACD cover (4 screws) remove the small metal access panel street side on the AC unit (1-2 screws) and check that the phone / 4-wire cable is properly seated in control board and is clean / free of dirt / dust / etc..