2 zone thermostat - sensor error

[Gtx Eng]

We have a 2021 27'FC. It was equipped with the Dometic thermostat mounted in the bedroom and a remote sensor mounted on the refrigerator bulkhead behind the dining TV. This is a 2 zone thermostat used to control two heat pumps, forward and aft.

The problem we are seeing as the first warm weather begins for us and the camper is that the refrigerator enclosure gets fairly warm (easily 90). The dining sensor mounted in the refrigerator bulkhead is reading 78 when the space temp is about 65.

Has anyone else encountered high tstat readings for the dining zone?

[twbucksr]

Its not an error. Your bulkhead sensor is picking up the heat generated from your tv.

We have been full time for several years now and thru trial and error, this is how we typically set the a/c’s up in the summer....

We have programmed our zones so that the unit over the bedroom (smaller capacity of the 2) runs during the day and the living room unit runs at night. This is done because the smaller unit will have to run longer to meet the set point which removes more moisture thus providing better comfort and efficiency.

On days when both units will need to run, we have the set point of the living room unit set 2 degrees higher so it only comes on when the bedroom unit can’t maintain set point and then both units are running at the same time.

We put a small fan on the bed to help move the air around during the day and move the fan to the base of the table leg at night.

[canuck_in_wa]

Yes! I was just looking into this today. 2021 FC 25RB with dual A/C units. Our furnace is in the same zone (2) that is wired to the temp sensor that reads high. When we first used the furnace we’d alternate between comfortable and freezing all night and I suspect this is the cause, or at least a contributing factor.

Right now, I have the trailer plugged in to 20A 110v shore power, and the fridge is on A/C. No heat sources have been active for a couple of days. Outside temp is 50F and inside zone 1 reads 54F but zone 2 is at 69F.

It seems like a huge design flaw to have the temp sensor in the refrigerator enclosure.

I am thinking that a quick fix would be to swap the sensors for zone 1 and zone 2 at the thermostat head unit. Or possibly just disconnect the second sensor so that everything reads from the one zone (not sure if that’s how it works). I am doubtful that multi zone sensors are needed in a tiny space with a single air volume.

Longer term that sensor needs to be relocated from the fridge cabinet.

[canuck_in_wa]

I ended up cutting a notch in the white cover and pulling the remote sensor wire through so that it’s sticking out a few inches. It’s now reading about 3 deg off from a reference thermometer.

The factory had just tied a knot in the wire so that it wouldn’t slip back into refrigerator cabinet, then covered it with the white slotted cover. I suspect that there is heat transfer happening from the cabinet to the cover due to everything being in close proximity and the sensor tip touching the cover.

I taped a bushing onto the wire so that it wouldn’t slip back into the cabinet. Also taped a piece of cardboard to the TV so that it doesn’t get direct sunlight (will have to adjust that later so it’s shaded on 3 sides).

The sensor does not seem to like having anything in contact with the final few inches of the wire. I originally had a bit of tape on there and it seemed to throw the reading off.

I’m planning to recheck tomorrow morning before the sun gets too high.

[Gtx Eng]

Finally just had to pull mine apart. It was as described. Three sensor was reading 90f and the heat pump would never cycle off. The refrigerator bulkhead is very warm, the refrigerator is running in auto electric mode, but does the same on LP. The cable feed directly beneath the sensor plays a large part in the inaccuracy.

The system began running properly within minutes of pulling the sensor out into free air.

So how do you get the teleportations down in the refrigerator compartment?