the fridge in our van appears to be getting an electricity and gas supply it will also run off the car battery, however it has an intermittent fault and at times does not keep the stuff in the fridge cold. The small freezer section works. My husband has tried to look at it without success, does anyone have any ideas it seems so strange that it is intermittent. The fridge is a wheel arch model and we have been quoted £500 to by new this doesn't seem worth it as the van is a 1992. please help