what kind of shed have you? is it insulated?
the fridge freezers can give trouble in cold weather. if the temperature in the shed goes below the temperature in the fridge then the freezer will cut out.
i got caught 2 years ago when the weather went to -3 and below. the temp in the shed dropped, the fridge cut out presumably to save energy but also cut out my freezer and i had a big box of sludge a few days later after everything defrosted. the freezer is well insulated so the temp outside didnt get in to keep it frozen, id have been better off letting the door of it open
to stop this i ended up having to put an oil filled electric rad out to the shed to keep the ambient temp up, i had it set to come on every 15mins to an hour depending on how cold it was due to get.