U.S. Pat. 4,509,335 to Griffin et al has a valve controlling the amount of cooled air flowing from an evaporator into a fresh food compartment for controlling the ratio of air flow to the fresh food compartment and a freezer compartment. The valve is disposed at an outlet of a duct through which air flows from a fan after passing over the evaporator to the fresh food compartment and is manually adjustable by a user.
It has been found that the user cannot always satisfactorily obtain a desired position of the valve. Thus, it is desired to prevent a user from adjusting the valve while still having the capability of adjusting the ratio of the cooled air from the evaporator to the freezer and fresh food compartments.