Thermostate/AC Problem

[phillyg]

Simple Dometic thermostat lost "comms" with AC and shows E1 code. Tried to reset by turning off completely, held down the + key, and pressed on/off button for three seconds, still show E1 code. Opened some windows, turned on a couple of fans, and put up with outside 84 degrees for a while. Roughly 2 hours later, the AC comes on. I had not shut down the stat and it was set to 69 degress. Anyone have any thoughts about this ghost issue?

[RMcNeal]

I had lots of problems with the CT thermostats from Dometic. Eventually replaced them with Micro Air and the problems are gone. I did run with the face plates removed from the original thermostats for a while to see if that was the problem. Apparently, the foam inside the face plate can get compressed and cause the contacts where the buttons are located to go all wonky. Try pulling the face plate straight off and run for a while without it. You can still operate it by touching the metal blade located under each button. It will not shock you.

[Andy Smith]

Robert, I seem to remember having this exact conversation and experience last year and was so glad you recommended the micro air easy touch t-stats. I've replaced both of mine with them and can't say how often I recommend them. Eventually the domectic ones got so bad you couldn't put the faceplate back on or it would go crazy. We did have the e1 error at one point with the bedroom AC, but for some reason it still worked fine, and eventually went away. Since I live FT in the montana, it was well worth the peace of mind and ease of use to swap out for the micro airs, in spite of their up front cost.

[phillyg]

So, last night I left the AC running with TS set at 68 degrees. This morning, same problem, showing code E1. Tried to reset TS several times, still E1. Left it on, 18 minutes later the AC started up. I haven't done anything else to the circuit. If it was a short somewhere between the TS and the AC control board, I would think it would lose comms more frequently, especially when there's vibration at the AC while running. I'm stumped.

BTW, I installed a Micro-air TS and it can't keep comms, and surprisingly, MA was of little help. They would only do email back and forth, no phoncons, and pushing that I wired it wrong or had user error. I'm not going to try it again till I find the real problem.

[RMcNeal]

That time delay almost sounds like a freeze lockout or bad freeze sensor. Have you been in the rooftop unit yet? The freeze sensor should be stuck in the fins of the condenser. If it has fallen out or if it's bad, there could be a long delay like that.

[phillyg]

Yeah, now it hasn't run in the past 20 hours or so, and the error code is staying on. I agree, it's time to go upstairs to have a look-see. Since the code is showing a comms error, I'll be looking for loose or corroded terminals, the sensor as suggested, and the model no. I'm good at replacing parts but weak on diagnostics, so I might have to call in (gasp!) a mobile tech that knows ACs. Thanks all for your suggestions.

[phillyg]

Following up, I had a mobile service come out and they've diagnosed a bad board in the AC unit. Waiting on them to get one and come back to install it.

[Chuck-n-Becky]

We had the same E1 error last year. I found a broken thermostat control wire in the AC on the roof. Works like a champ since.