Adding 2nd AC

[Tommy722]

We have HM305RL 2017 that has one AC and a 2nd opening in bedroom that is pre-wired with power and what appears to be control line. Have a few questions.

We have installed an EasyTouch thermostat and discovered that it only has serial comm line out. This leads us to believe it talks to a control unit somewhere that has the actual control lines to AC and Heat devices.

Question 1. Assuming the control unit I described exists where can we get info about the control line found at this 2nd AC point?

We would ideally like a 2nd AC to normally use existing vent, but it seems possible to make it feed just the bedroom if desired.

Question 2. If we obtain an AC unit described as non-ducted then it will obviously have an inside assembly that provides return cooled air, but if we leave the return air canal open to the duct of the RV we must only close the return air vents and our 2nd AC will be going into duct and supplementing the 1st AC. Sound workable, reasonable?

All input appreciated.
Thanks
Tom and Linda

[rohrmann]

On our rig, we have two A/C's, and there is a control box below each A/C that has a comm cable connection. The comm cable connects at the thermostat, goes to the zone 1 A/C, which on our rig is the one over the living room at the rear. From that box, a cable goes to the furnace and also a comm cable goes to the zone 2 A/C at the front of the rig over the bedroom. The boxes have a dip switch on the circuit board, and the zone 2 dip switch has one switch marked zone 2 that is switched on, all the others on that dip switch are switched to the off position. The A/C's are both Dometic and the thermostat is the CCC2 that works with the control boxes. This is what the control box looks like. https://www.amazon.com/Dometic-33120...%2C1051&sr=8-4