How to test & replace the flipper mullion or mullion rail on a Whirlpool-built french door refrigerator

The flipper mullion, or mullion rail, keeps your Whirlpool French door refrigerator cool by sealing the gap between the two doors, stopping warm air from sneaking in and affecting the fridge’s temperature. Over time, this part can wear out or get damaged, making your fridge work harder to stay cold. We’ll show you how to test and replace the flipper mullion if needed, so your fridge stays sealed.

If you find out that you need any replacement parts for your appliance, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

Important: The error code information provided in this article may not apply to your specific appliance model. The disassembly information is based on model KFIS29PBMS02. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

Tools and materials

• Multimeter
• Nut driver
• Flathead screwdriver

Important: The specific tools required may vary depending on the model of your appliance and the type of fasteners used on it. Always consult the user manual or refer to any specific instructions provided by the manufacturer for the recommended tools for your appliance model.

Read more: Tips for Buying a Used Refrigerator: Quality On A Budget 

Safety precautions

When working on any appliance, remember to keep safety first. Here are some tips to keep in mind: 

• Always power off and unplug your appliance or switch off the circuit breaker before attempting any maintenance or replacement work. This keeps you safe by preventing any risk of injury from electric shock.
• Wear insulated work gloves to protect your hands from sharp metal parts, pinching hazards and debris.
• Take your time and don’t rush while working to prevent accidents and personal injuries.
• Work in a well-lit area so you can clearly see and access the interior parts.
• Clear your workspace of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with bare wet hands. Make sure the work area is completely dry.
• Check your user manual to see if there are specific installation or safety instructions for your part or appliance. 
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause injury.
• Wear safety glasses when working with chemicals, dust or cleaning large debris to prevent injury. 
• If the appliance has recently been used, give it plenty of time for any heating parts to cool down before working on it. 
• Take pictures or make a note of wiring terminals or other connections before disconnecting to prevent any problems with reassembly.
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.

Read more: How to Level a Refrigerator in 6 Easy Steps 

Testing and replacement steps

Step 1: Access the mullion wiring

1. Start by unplugging the refrigerator or turning off the breaker to disconnect the power.
2. Open the left door of the refrigerator to access the flipper mullion.
3. Flip the mullion to the open position to expose the mounting screw that holds the middle hinge of the mullion to the door.
4. Use a 1/4-inch nut driver to remove the mounting screw.
5. Push the mullion upward from the bottom to disengage it from the upper and lower mounting tabs.
6. Push the mullion away from the door to remove the middle cover that was held by the screw.
7. Disconnect the connector that powers the mullion.

Step 2: Test the flipper mullion

1. Set your multimeter to measure resistance (ohms), which is represented by an upside-down horseshoe symbol.
2. Place the multimeter leads on each terminal going to the mullion. You should see a reading between 20 and 30 ohms.

If the reading is outside this range, the mullion needs to be replaced. If the reading is correct, move on to testing the voltage.

Step 3: Test for voltage

LIVE VOLTAGE WARNING: For this test, the appliance needs to be plugged in and powered on. Please be very careful to protect yourself from electric shock, which has the potential to cause serious injuries. Don’t ever test live voltage if you’re uncomfortable using a multimeter.

1. Plug the refrigerator back in to test for live voltage.
2. Clear any “PO” or “PF” error messages on the display by pressing and holding the two buttons farthest to the left along the bottom of the user interface. A countdown from 3 should appear, and the display should start flashing “01”.
3. Press the 5th button from the left (with a plus sign) to advance to test 35, which runs the vertical mullion heater. Ensure the display reads “01”; if not, press the options button to switch it from “02” to “01”.
4. Set your multimeter to read DC voltage and place the leads in the connector coming from the door. You should see 12-15 volts DC.

If you don’t get this voltage, the user interface in the door will need to be replaced.

Step 4: Replace the flipper mullion

1. Unplug the refrigerator or turn off the breaker before replacing the part.
2. Connect the flipper mullion heater harness to the harness coming from the door.
3. Align the mullion with the center cover and the upper and lower mounting tabs.
4. Slide the mullion down, making sure all mounting points are aligned and in place.
5. Use the 1/4-inch nut driver to reinstall the screw that holds the center cover to the door.
6. Once everything is reassembled, plug the refrigerator back in or flip the breaker back on to restore power.

Read more: How To Prevent And Fix A Frozen Refrigerator Water Line 

Additional information

Thank you for reading! We hope this guide helped you get your refrigerator working again.

If you have any other appliance repair needs or projects, don’t hesitate to explore our other troubleshooting guides and videos. 

If you need replacement parts or some extra help with ordering them, grab your model number and head over to AppliancePartsPros.com, where you can chat with a pro, read our DIY blog and more.

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