Freezer not cold enough to freeze anything. Refrigerator temperature is normal. Replaced the Main Circuit Board. No change. Cleaned to coils. Service manual says to put both freezer and fridge readouts at 5 and hold all four buttons in for 3 seconds. Each time I do this the refer readout drops to 4 and no diagnostic readout (flashing 0's). What needs to be done to make this unit enter the diagnostic mode? Any suggestions on what may be the problem with the freezer side? Apparently this model has been known for problems with the Main Control Board. No problem since this unit was put in service in 2005.