Wanted to post back and let provide status.
We were able to complete trip and have had the trailer parked in the driveway. Fridge is empty and we put a remote thermometer in so we can monitor the temperature from the house. Replaced thermistor and ensured all connections are clean and firm on circuit board. On both electric and gas it cools fine. Then, after 48 hours it appears to enter a defrost cycle. The defrost cycle seems to last a couple of hours which in 90+ weather (no AC running so interior is hot too) allows it to warm up 10+ degrees. It will then resume cooling.
So, I will either live with it (and perhaps cycle off fridge every morning to avoid 48 hour defrost cycle) or swap out the circuit board.
Thanks again for support and feedback while chasing this down.
Stu
