I have recently purchased a used Cheyenne 840S, the problem I have is that the fridge only works on 230VAC. When I select either auto or 12VDC or gas the fridge only ever works with 230VAC when hooked up. I tried looking for a competent wiring diagram on the Autotrail web site and was confronted by the same vague sketches that are in the handbook. Can anyone help, I presume that the gas will only work if there is a 12VDC supply, when switched to gas I cannot hear any attempts at ignition. The fridge is a Thetford N150.