Whirlpool Refrigerator Defrost Timer WP4391974, Fixes Frost Build-Up & Failed Defrost Cycles

The Whirlpool WP4391974 Defrost Timer controls the automatic defrost cycle in your refrigerator, cycling the defrost heater on and off at timed intervals to prevent frost accumulation on the evaporator coils. It replaces 4391974, W10124406, 215846604, 00-NRK4, 00-NRK5, 045548-01, 045548-02, 1107752, 13-5699, 13-8938, 14205043, 14205050, 24399-1, 26250-1, 26308-2, 27039-1, 27039-2, 27039-3, 27039-5, 29811-3, 4341046, 4355375, 4355378, 4355379, 4355380, 54113-1, 54113-10, 54113-11, 54113-4, 54113-6, 55448-1, 55448-3, 55448-4, 55467-1, 55467-5, 58194-1, 65322-1, 65322-2, 65702-1, 65702-2, 66128-1, 66128-2, 66556-1, 66556-2, 66556-3, 66556-4, 66556-5, 66556-6, 66556-7, 69217192, 69381715, 69543-1, 831394, RA43819-1, RA43869-1, RA43870-1, RA43948-1, Y00NRK4, Y00NRK5, Y04554801, Y04554802 when fitment is confirmed by the full appliance model number. An XPart aftermarket option (Supco SPA1401AD) is also available.

Is This the Right Part?

Confirm the complete model number before ordering. Defrost timers vary by cycle duration, voltage rating, terminal configuration, and mounting style. Do not order by part number alone.

Common Symptoms

• Excessive frost or ice build-up on the back wall of the freezer compartment
• Refrigerator not cooling properly — freezer cold but fridge section warm
• Refrigerator runs constantly without cycling off
• Defrost heater never activates — evaporator coils completely iced over

Check Before Replacing

• Manually advance the defrost timer with a screwdriver — if the defrost heater activates, the timer is confirmed faulty
• Test the defrost heater with a multimeter for continuity — a burned-out heater can mimic a failed timer
• Check the defrost thermostat (limit thermostat) — an open thermostat will prevent the heater from firing even with a good timer
• Inspect the wiring harness and timer terminals for corrosion, burn marks, or loose connections

Part Details

Installation Notes

1. Disconnect power to the refrigerator before beginning.
2. Photograph the timer wiring harness, terminal positions, and mounting orientation before removal.
3. Compare the replacement timer with the original — confirm terminal count, cycle duration, and voltage rating match.
4. Inspect the wiring harness, defrost heater, and thermostat for damage before installing the new timer.
5. After installation, restore power and manually advance the timer to verify the defrost cycle activates correctly.

If you are unsure about wiring or terminal identification, a qualified appliance technician can complete this repair quickly and safely.

Verified Compatible Models

Model numbers not confirmed — contact us with your full model number (including all suffixes and revision digits) to verify fitment before ordering.

Fitment reminder: Match the complete model number, including suffixes and revision digits, before ordering. Additional compatible models may exist — contact us if your model is not listed.