Chuck for Model Number rf220nctaww Samsung Rf220nctaww freezer compartment was iced over enough to make the evaporator fan rattle. The temperature rose to 60 *. Unplugged unit and let defrost. After start it cools to 30+/- then rises back up to 40 to 50. Had diagnostic code F4. Damper opens and closes and the evaporator fan starts after a 14 second delay when the refrigerator doors open and are closed. Had f1-f2-f3-f4 diagnostic lights on at last diagnostic test.
Answer Chuck, you will want to test the sensors in the freezer section by accessing the main control at the back of the unit. At the main control, with a multimeter set to DC voltage, you will want to test the ambient sensor by placing the red probe of a multimeter on connection CN78 pin 8 to pin 12 with the black probe. The voltage reading should be between 1 to 4.5VDC. If this fails, then the main control is bad. You will then want to test the freezer sensor from CN30 pin 4 to CN78 pin 7 for the resistance values of 10823ohms at 41 degrees to 8867 ohms at 50 degrees. If the resistance fails to read accordingly, then the freezer thermistor has failed. The freezer defrost sensor would then be checked at CN30 pin 5 to CN78 pin 7 and it should read greater than 15076 ohms with the evaporator frozen up. If these all check good, then the defrost heater and bi-metal would need to be tested directly at the heater assembly and it should have a resistance of 63 ohms. If any of these components have failed, they would need to be replaced. If these components have all passed testing, then the likely cause would be the main control. The revision number of your refrigerator would be needed for accurate part numbers in regards to which part number would be needed for repair. Read More... Answered by AppliancePartsPros.com | Thursday, June 20, 2019