You have the 2022 Tiffin Open Road? If so, you have a problem. A Tiffin in 85 ambient will freeze you out with 2 AC units. I would set the front at 65 degrees and the rear at 75 and then see what happens. Your Tiffin has the inside temp sensors mounted in the ceiling drivers side next to a cold air vent. 1 in the Bedroom and 1 in the living room. Also, turn the rear OFF and run the front at 65 degrees. Test after at least 1 hour. The air output in the living room should be at least 60 degree output. It will probably be in the 50 to 55 range. Your 42 and 43 are NOT correct or accurate. Your Thermometer is not designed for what you are testing. The Delta difference is 18 to 22 degrees. That means at your 42, the warm INPUT would be 62 degrees which is enough to freeze you out. So, based on my 42 years as a RV Tech (Tiffin dealer tech also), your temp measurements are not good/correct at all. Doug
PS you state digital thermometer set on house mode. NEVER heard of that type thermometer and I would not use such a appliance. Click this link for what you should use. ALSO, you CANNOT use a IR type Thermometer.
https://www.oreillyauto.com/detail/c/robinair/tools---equipment/measuring-tools/thermometers/bbe3c38dae59/robinair-thermometer/rob0/43230?pos=8