Thank you all for your suggestions.
TreeClimber,
I have popped the switch out, it is a simple 12 v. rocker switch, that has the 'on' side painted red. It has continuity when turned on.
RetiredCamper47,
I was leaning towards a fridge switch, but was wondering why nothing happened when turned on. If the fridge needs to get 'warmed up' for it to come on, this would explain why nothing is happening when it is turned on.
I will turn it on when using the fridge and see if it comes on, when we are camping.
I will post my findings, for future reference ...
Thx
Rick