Join Date: Sep 2013
Location: South Devon
My Motorhome: Bessacarr E725
Thanked 159 Times in 138 Posts
The relay that directs 12 volts to the fridge (for temperature maintenance) is usually in the engine compartment. I know mine is, and it also operates the auto step retract.
The OP said he was getting a buzzing noise, and I assume he meant from the fridge itself.
As I understand things, a fridge has 2 12volt supplies. One which comes on with the hab electrics and allows the controls and interior light to work. The other with the engine running, and maintains the temperature whilst driving.
I'm daft and proud of it.