Frigidaire Refrigerator: Troubleshooting Door Mullion... | appliancefaults.com

Technical Background:

The mullion heater prevents condensation by warming the area around the door, preventing moist air from condensing on the cooler surfaces. The electronic control board (ECB) typically controls the heater, activating it based on door switch status and potentially humidity levels. Voltage is supplied to the heater through a wiring harness running through the door hinge area. If the door switch isn't triggering correctly, the heater won't receive the voltage to activate.

Symptoms:

The homeowner observes condensation forming on the refrigerator door, particularly around the mullion (the center strip between the refrigerator and freezer compartments). This indicates the mullion heater is not functioning properly.

Possible Causes:

Defective mullion heater
Faulty door switch
Wiring harness damage in the door hinge area
Malfunctioning electronic control board (ECB)
Open thermal fuse on the heater circuit
Loose wiring connection

Solution:

1

Disconnect power to the refrigerator at the breaker panel. Verify 0V AC at the outlet.
2

Locate the mullion heater. It's usually behind an access panel on the refrigerator door. You may need a 1/4-inch nut driver to remove the access panel screws.
3

Using a multimeter, check the mullion heater for continuity. An open circuit indicates a failed heater. Expect a resistance reading between 20-50 ohms.
4

Inspect the wiring harness leading to the mullion heater, especially in the door hinge area, for any signs of damage or breaks.
5

Check the door switch. With the door open, the switch should be open; when closed, it should be closed. Use a multimeter to test for continuity.
6

If the heater and wiring are good, suspect the electronic control board (ECB). Refer to the wiring diagram for testing voltage output to the mullion heater (typically 120V AC). If no voltage is present when the door is closed, the ECB may be faulty. Replace accordingly.
7

Check for a thermal fuse inline with the heater. Use a multimeter to verify continuity; replace if open.

Safety Warning:

Disconnect power to the refrigerator before performing any diagnostic or repair procedures. High voltage is present in the appliance. Follow Lock Out/Tag Out (LOTO) procedures to prevent accidental re-energization.

Prevention:

Regularly clean the door seals to ensure a tight seal, reducing the likelihood of condensation forming. Inspect the door hinge wiring harness periodically for any signs of wear and tear.

Expert Tip:

Some Frigidaire models have a service mode that allows you to manually activate the mullion heater for testing purposes. Consult the service manual for your specific model to access this feature. Often involves a specific sequence of button presses.

Frequently Asked Questions

•What is the part number for the replacement mullion heater on my model?

The part number can be found on the appliance's parts diagram, located either inside the unit or on the manufacturer's website using your specific model number.

•How do I access the electronic control board?

The ECB is usually located behind a panel on the rear of the refrigerator. Disconnect power before accessing. You will likely need a 5/16-inch socket or nut driver.

•Is it possible to repair the wiring harness instead of replacing it?

Yes, if the damage is minor, you can repair the harness using appropriate connectors and wiring. However, if the damage is extensive, replacement is recommended.

Frigidaire Refrigerator: Troubleshooting Door Mullion Heater & Condensation

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•What is the part number for the replacement mullion heater on my model?

•How do I access the electronic control board?

•Is it possible to repair the wiring harness instead of replacing it?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: