I've got a 2019 Thor Synergy 24MB and here's how I fixed it:
1) I studied the wiring diagrams and found that the temp sensor wire is Orange / White
2) I removed the drawer which was above the AC Breaker / 12V Fuse Box, which gave me access to the "multiplex planel".
3) I found the Orange / White wire and wiggled the wire where it's attached to the connector that plugs into the multiplex panel. Voila! The Temp Sensor started working again.
*** I seem to have to do this fix every few weeks, so I need to study that wiring connector more closely to make a permanent fix.
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