Originally Posted by denville
The thermostat does not have communications to the control board on the AC. When you reset the thermostat you lost zone 2 because of the this. I had the same problem on mine, only I had to pull the cover off the AC to reset the connector on the AC unit. Luckly for me that was my problem. Hope your as lucky
I had the same problem several times until I figured out why.
E2 is a loss on communication between t-stat and A/C or between both A/C units. In my case, the front A/C unit would start to cycle on & off and finally stay off with the E2 code then, the rear would do the same and eventually the whole system would shut down (as defined in Dometic literature). The 2 A/C's communicate with each other through the t-stat so if 1 has a communication problem and the 2nd one can't talk to the 1st one, they will both shut down.
After 3 calls to my mobile tech (each time he was able to get it working for about 1 - 6 months) I finally went up on the roof with him to see what he did. We removed the cover on the front A/C unit then removed the 8-10 screws on the curved cover for the air return (front of the unit). In there, are a bunch of communication cabled (telephone type wire) with modular plugs. He unplugged each one and inspected it, cleaned it with a small brush and plugged it back in. One of the cable ends was corroded. After cleaning this (actually he cut off the end and replaced the connector) and reconnecting, BOTH A/C's started.
The 4th time, I went up myself but this time, I cleaned, taped the connections with good electrical tape and ziptied all the wires up and away from the evaporator core (moisture) and drip tray. It's been 10 months since I did that and there have been no further problems.
The reason you lost the front (zone 2) A/C after reinitializing the t-stat is because the t-stat then "looked" for systems connected to it. When it couldn't find the front A/C (no communication) but found the rear A/C (zone 1), it thinks everything is ok, only one zone and will allow the one A/C to run.
If you feel capable and can't see the comm cables from the inside (ducted A/C system) and you're able, go up on the roof and do what I did.
Good luck and keep us informed.