After manually defrosting seemed to have fixed problem of warm refrigerator compartment and blocked drain tube due to freezer ice buildup. plugging in refrigerator and set cooling touch pad to 3. after a while the setting jumps to 5 (coldest) and cannot be adjusted. temp in refrigerator compartment is 32 to 34. if i unplug it for a minute, it will be automatically reset to 3 but returns to 5 after half a day. at this point the touch pad will not respond and stays at 5. any idea what part has failed? thanks.