Hello, my name is George..The RM275 is an absorption fridge that uses varying types of Ammonia in its cooling process. Sometimes this can be caused when the chemicals of the fridge fail to separate.
However, this is usually caused by leaking refrigerant at the rear of the fridge.Here is a page to teach you a little about how they work
It would be advisable to have the fridge tested by an appropriately qualified person. Such a person could be advised to you from your local caravan service centre.
Kindly be patient whilst awaiting any responses from me as I'm not constantly available.