Hi, Our Outback Swan is a 2012 and our fridge is a Thetford. This is my observation and I suggest all you guys that think your fridge is running from the on board battery from factory to check into it properly, because that was my assumption up until the final leg of our 3 month trip away. This leg of the trip was a straight through drive from Coral Bay to Perth 12 1/2hrs non stop (appart from fuel etc) 1140ish K's in one day. Up until this point of the trip the fridge and freezer had remained cold for all legs of the trip although I noticed there was no heat from the top outside vent and on one 700km day we had some water leak out the fridge from the spill tray, but I assumed all was fine.
On the big trip home the freezer defrosted quite a lot so it got me thinking, so when I had the chance I got out my multi meter and started testing. I should also let you know I have an isolator wired into my car 6B&S wired through a 50amp Anderson plug straight to the Swans battery. The battery is then wired to the on board setec.
Now this is what I have worked out. If you look under the out side floor on the drivers side just in front of the fridge vent you will find a metal guard and under the guard will be a mess of wires. If its like mine you will find two stupid plastic double screw wire connectors. One to join all the earths and one for the +'s. I removed these connectors soldered and covered these joins with dual wall heat shrink before our trip, but didn't bother to check everything was wired how I thought it was if that makes sense? Basically there is no connection from the on board camper battery and the fridge. I also found the positive and negative connectors behind the fridge to be backwards, so it is good that it wasn't hooked up straight away.
OK deep breath sorry for the long winded response so far, but unfortunately I'm not there yet!!! The factory wiring allows for the campers battery to be charged via the Black wire in the 7 pin trailer plug and also this is the wire that they power your fridge from. Now back to under the floor stupid connectors. The positive connector has three wires in it. The black wire from the trailer plug and two red wires one that goes direct to the fridge and the other goes direct to the positive input on the setec.
Now the quick fix although your camper battery can be drained if your not careful with this method is........disconnect the red wire from the positive input on your Setec charger and connect it direct to your camper battery (a fuse in this line may be a good idea). This method has issues that I'll go into another post but unless you have a fridge motion switch etc you run the risk of draining the camper battery.
OK if you need any further info or clarification or even photos let me know. It bugged the crap out of me and took me a bit to track all the wires (the old continuity tester got a work out), but I can assure you with that simple fix the fridge works perfect even from a warm start the temp dropped in the fridge when connected to the car and the top fridge vent outside was warm (took about half an hour for the heat exchanger to start to really work though.