Running fridge from the engine

Hello, looking for advice on using the fridge in the VW Trident Autosleeper. We've never seen any sign of the fridge working when it is set to the 12V mode- the light on the switch doesn't come on, and neither does it seem to get cold when it's switched to on on 12v mode and the engine is running. I can make it work on the gas setting and I've not yet tried using it when plugged in on the 240v setting. Should the light on the switch come on when it's on and the engine is running? And can it cool down the fridge or is it more to keep it cool once cooked down by the gas or 240v setting? Many thanks for your advice!

12volt, only keeps it cold after you have had it on gas or EHU,  a few hours beforehand. My  fridge is plugged in all the time on the drive.

In my Amethyst I do not have any lights at all no matter which ever fuel is used for the fridge. perhaps the bulb has failed or a fuse failed. on yours.

Does the 12v switch on the zig (or other) unit need to be switched to on as well as the switch on the fridge itself? (Not without engine running of course)

Not familiar with the Trident wiring but on Symphony there are two fuses in engine bay near battery. One is for the fridge and the other for split charge. Where these fuses are on a Trident I don't know but they are the commonest reason for it not running when engine on.

Hi, 
On my old 2001 symbol the fridge cooling was very effective with the engine running, arriving on site the freezer compartment was always iced, those who's fridges don't do this probably have a fault of some sort, 
Chris

Question for you please Chris
When running the fridge on 12 volt whilst driving does the 12v switch on the zig unit need to be on as well as the fridge itself switched to 12v?
Hope that makes sense
Cheers
Rob

Hi, 
As I recall the position of the zig switch made no difference, personally I only ever switched mine off when I was parking up and the van was not being used, 
Chris

Quite agree, we never pre cool our fridge, simply select 12v then drive off. Always v cold in there on arrival. Pretty sure there is no temp control on 12v, but, either way its very cold even after a relatively short journey.
We tried an experiment last trip to Spain, 25 hr ferry, no poss power to fridge. We froze a 2 lts bottle of water at home and left it in the freezer compartment, night stop pre ferry, no EHU, 25 hrs on ferry, bottle about half frozen on arrival in Spain. Drove circa 100miles to first N/S, bottle totally frozen on arrival!!
AND it stayed that way for 18 days in Spain and was only half frozen after the return 25hr ferry then the drive back to here!!
Must say I was impressed!

Good feedback - thanks to everyone. Will try mine out more carefully

Brilliant, thanks everyone, sounds like it might be a fuse problem. Anyone got experience of where the fuse for the fridge 12V connection would be in the Trident?

Hi Jessok, 
I had the same problem on my early trooper, it was the relay that activates when the engine is running to power the 12v on the fridge.
Chris