I don't have that particular type of unit, nor have I worked on one, but, without a remote sensor (usually used for "zone" monitoring on large RV's), I would have to guess that the sensor is probably in your thermostat mounted on the wall... If anyone knows for sure, please chime in
Most likely it is contained internally to the Comfort Control Center (the thermostat). I'm not sure if it is a serviceable piece or you have to replace the entire thermostat. Dometic would be my first "port of call" to find out:
For RV products
Customer Support Center
P.O. Box 490
Elkhart, IN 46515
If it is in the thermostat, they may be able to FedEx one to you or if you are really desperate, you may be able to get a replacement locally or substitute a different thermostat from Wally World, etc... If it is part of the compressor control module (in the ceiling harness), then it would be a different matter...may be user serviceable, may require a professional (or semi-pro handyman) to be able to locate, remove and replace the part...
Sorry I can't be of more help, but, anything else I could or would tell you would just be a WAG...