Clicking noise when towing?

[Len_Cuff]

Seem to be suddenly getting a clicking noise (habitation relay?) when we connect the car and turn on the fridge.
Fridge shows blue solid and keeps everything cold but just wondered what it might be?
Van is an Adria Adora 612DP and the noise appears to come from behind the fridge.

 

[Damian]

It is the fridge relay cutting in and out until the voltage reaches about 14v.
Once you increase revs it should stop the clicking.