Flaky Furnace Thermostat

CarnationSailor wrote:
I replaced the thermostat with the same model, and the problem did NOT go away. Not a big surprise, but a necessary troubleshooting step.

On the iRV2 Forum, people were having a similar problem with a different model thermostat that they thought was caused by "noise" on the rig's ground line. Supposedly a "noisy" LED could cause the problem. Some put a filter on the ground line, but had limited success. In my case, when the t-stat jumps in the middle of the night, there are no lights on.

I expect that the 12-volts gets to the t-stat via the furnace itself. I wonder if some circuit in the furnace is messing with the 12-volts?

Doug,

I did all the steps you suggested except for "checking connections at AC control board". Assuming you are referring to the air conditioner, how does this relate to the furnace problem?

Sure could use some more ideas.

Thanks

The AC control board is the gateway for AC and Furnace control. On some RV's the 12 volt power for the wall tstat comes from the AC control harness 12 volt power supply. I have never heard of RF from lights and such causing the wall tstat to loose memory and default to 72 degrees. The RF problem is usually for RV's OVER 10 years old. RVP has installed update filters and chokes on the wall tstats to prevent RF problems. The older problems caused certain models to go to "00" on the LCD display. You don't have this model tstat. As I stated, defaulting to 72 degrees points to a 12 volt connection problem. Doug