Air Conditioner: Remote Sensor Location

We can’t find out remote temperature sensor in the bedroom (zone 2). This is more than an academic question…. the control of the rear AC is not good and the bedroom temperature is often much lower than the Comfort Control setting. We have looked high and low (literally) for that sensor… no luck.

Yesterday James Triana directed me to the circuit board on the rear AC unit (access from the roof) and asked if a sensor was connected to that board (at p4 according to the circuit diagram). See below… there is something plugged into the board at that point. But when I went below and looked for that lead (easy to see since it has two small white wires) in the bedroom side of the AC unit, all I find is a connector where I think the remote sensor attaches. Also when I look in the roof area near the TV where the sensor should run from the AC unit to the wall near the bedroom TV, there is nothing there that looks like a sensor. So James and I have come to the conclusion that our coach was built without a rear sensor. But how could that be?

From what I have read a sensor is required for a two AC unit installation. And the Comfort Control does seem to control the rear AC unit (turns it on and off). I would appreciate some info on how the Comfort Control thermostat can work without a rear temperature sensor. I will probably get a sensor and install it near the AC intake…. not ideal, but better than nothing. But before doing that I want to understand the system better.

In our coach, that small connector goes to what we think are the white wires in the left of your photo, which disappear into the coach in the direction of our temperature sensor. Can you find where they terminate (either end) on yours? Michelle 

I am 99.9% sure there is no remote sensor on our rear AC unit. I can see where the wires to the sensor plug into the AC unit circuit board and I can see where those wires terminate inside the AC unit on the bedroom side. There is a connector there for the actual sensor, but there is nothing there. See the photo below.

So the question is…. how can my two-zone motor home Comfort Control thermostat operate without a rear sensor? Could it have been set up in some special way to do so? I will install a sensor (if I can find one) but do I need to do anything else. To give you an idea of the problem, we were out this morning and the rear (zone 2) setting was 75 degrees. When we got home the bedroom was at 71.5 degrees.

According to James Triana, I can buy another sensor and plug it into the connector. The difficult part will be running the sensor to a logical location (usually the front corner of the bedroom, passenger side, in our floor plan). James also mentioned some wire conduits that run from the AC to that corner…..see photo below. I have not tried to run anything through them but will check them out.