Servis M76845 Fridge/Freezer?

Just purchased the above, s/hand.Although it resides in a fairly cold out building,it will run down to temp,then stop.This tells me that the T/stat is ok,but it will not re-start on demand.The few items I have in the freezer become soft because of the length of time the system is not running.Can you tell me if this is normal,or is there a problem with the unit being in a cold shed,or could there be other tech issues ?