Dometic fridge not working ???

i have a Dometic fridge in my 2005 caravan and earlier this season it appeared to stop working although all the lights both inside and out appear to be functioning ok, I have tried it on gas and I think that you can hear it ignite but no cooling and mains electric is the same in that it appears to be functioning but no cooling. I was wondering if it was a faulty thermostat ??? Anyone got any ideas ???

Gelders
June 2009