One of the questions that I’m asked from time to time is about the 12 volt circuit from the tow car to the caravan that powers the fridge, is how to find any problems that could be the cause of the fridge not working at its normal capacity. There are a few checks that can be done on the fridge first before having to start to look for other reasons why the fridge is not functioning to full capacity when towing.
I have written hopefully a simple guide to checking the circuit tracing the voltage drops and locating where the problem could lie. It will take some time and a basic understanding of how to use a multi-meter is required but it should either help you find the problem(s) or confirm that there is nothing wrong with the wiring and you can stat to look for other possible issues.
I hope you find it helpful.