The 3 way (gas/elec/12volt) fridge in caravans require a very high current 12 volt power supply to keep the fridge icy cold in transport. You may not know this but this circuit comes from your tow vehicle and not your caravan’s battery. It can be in the 12 pin plug or in an Anderson plug connection. The gauge of wiring for this circuit MUST SUPPORT ITS REQUIRED CURRENT DRAW all the way from starter battery to fridge. So, when we run the vehicle cable, we always take this into account. If you have an Automatic 3 way fridge (AES) both Thetford or Dometic, you will also require an extra sensing wire from the vehicle to tell the fridge to turn over to 12 volt and start pulling high current from the vehicle when the engine is running.
Upon shutting the engine down, the sensing wire should isolate and in turn the fridge will stop pulling power from the vehicle. 15 mins after this, the fridge will try and ignite onto GAS. This is the automatic feature and is there for your safety. When you start your vehicle again, it will turn back onto 12 volt automatically. As we understand caravan appliances and circuits we make sure the vehicle is setup correctly to suit the required application.