Apart from owning a RM4605, I know very little and I not a tradie.
Our caravan is a 2012 model and our problems have been 12 volt electrical only.
We purchased the caravan secondhand when nearly 4 years old with most of its life in storage, it had the 12 volt power feed though a anderson plug which gave me grief as the wiring was of poor quality (cheap wire from Chinaland). After replacing and setting the supply up using the solar fed house batteries on a much shorter cable my problems were solved.
We are enjoying the 3 way frig and would not hesitate to having another
Gas problems I would be in serious trouble requiring a Professional Gas Refrigerator person to rectify any problems in that area and that is where I would be heading.
Does the Day/night Temperature have any impact on the 48 hours shut down.
Am thinking of a dry electrical joint and that takes 48 hours of current thru the joint to heat up and go open circuit eg and a cool day and night longer to cut out time.
