Thermostat inaccurate by several degrees

[CactusFlower]

2023 Grand Design Transcend, this is my full time home right now.

New to RV'ing and non-technical person here . . . I set the the thermostat to turn on the a/c at 80 degrees. I come home and it's very hot inside. Temperature on the thermostat says 84 before a/c clicks on. The actual temp in the RV was 87.

Interestingly enough, when it's cooler in the mornings, the temperature on the thermostat is accurate to the true temp inside the RV. It's only when it starts to get warm, there is a huge difference between actual indoor temp and what the thermostat shows is the temp. Up to 7 degrees off. What is going on?

For the safety of the pets who stay inside when I'm gone I have installed a window a/c unit in the main room. That cheap unit is working much better at turning on and off according to the true temperatures.

[ncitro]

Is it a Furrion unit? There was discussion with those about relocating the sensor for the thermostat from the plenum on the unit down through the ceiling to make it more accurate.

[CactusFlower]

Yes it is, and I just did a search and found this. It looks like some of the models have the sensors on the thermostat and some have them on the unit itself. I'll have to wait until after work and I'll check it out. This would make total sense as to why the difference. However I'm not tech savvy enough to do the repair. What a bad design! Especially living in the southwest, the sun heats up the exterior very quickly, and at night it cools off very quickly. So the temp sensor is all over the place depending on time of day and weather outside. This was from this morning at 8AM. 8 degree difference already. I did not have the A/C's running at this time when I took the photos. I didn't think to check sensor location, I had assumed it was in the thermostat--- I'll post an update when I get home.

[CactusFlower]

I just thought of something else---- sometimes I open up the vent on the unit to blow air just in the main room and not the bedrooms. I wonder if the cold air blowing out is being immediately pulled back into the unit and showing a cooler temp than is actually in the room? This thing is all over the place. Maddening.

[Reacher]

I had the same issue with both heating and cooling mode with the newer type Furrion/Lippert AC thermostat and control unit. I installed the the AC sensor relocation kit (available online for 30-40 dollars). This solved the AC issue. Furrion/Lippert's customer service said that the unit was designed to work by leaving the fan on 24/7. Not my idea of working right. The furnace issue was corrected when I installed an old school analog suburban/Atwood thermostat. Now HVAC works as it should. In the future I plan to steer clear of any RV with Furrion/Lippert appliances.