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Error code · Microwave

Whirlpool Built-In Microwave Help for Code 4d42: Fan Speed and Airflow Too High

Whirlpool built-in microwaves and microwave drawers, such as the WMC50522AS, display 4d42 when the cooling fan speed is too high. The areas to look at are an airflow restriction, the oven cooling fan itself, or its…

Medium · inspection needed
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Code
4d42
Appliance
Microwave
Brand
Whirlpool
Warranty
30-day workmanship

What 4d42 means

Whirlpool built-in microwaves and microwave drawers, such as the WMC50522AS, display 4d42 when the cooling fan speed is too high. The areas to look at are an airflow restriction, the oven cooling fan itself, or its wiring. The code tells you the control is not seeing the fan speed it expects, so the oven shows the message and may limit or stop heating until the reading is normal.

Common causes of 4d42

  • Airflow restriction changing how the fan behaves
  • Oven cooling fan speed outside the expected range
  • Fan harness connection that has loosened or worn
  • Short-lived condition that a restart clears
✓ One safe check you can try

1. Look for anything blocking the vents or the airflow around the microwave. 2. Switch the breaker off for one minute. 3. Switch it on again. 4. Stay with the oven for a minute and see whether 4d42 shows up again. 5. Verify normal operation.

! Why to stop there
  • If 4d42 comes back, we test the fan speed feedback and look at the airflow path
  • Wiring to the fan gets checked at the same visit
  • You approve the written price first, and we warrant workmanship for 30 days
Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.
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Other Microwave codes

FC E3Whirlpool Over-the-range Microwave Showing FC E3 for Wi-Fi: Module Check FC E7Whirlpool OTR Microwave Connection Code FC E7: Appliance Not Reaching the Internet FC E8Whirlpool OTR Microwave Registration Code FC E8: Entry Mistake FCE8Whirlpool Over-the-range Microwave Registration, FCE8: Wrong Model Selected Feature Not Available or Fault DetectedWhirlpool Built-in Microwave Message "Feature Not Available": Retry or Cut Power LOCWhirlpool Microwave LOC on the Display: Control Lock Is On PFWhirlpool Over-the-range Microwave Showing PF: Power Failure Indicator Press Cancel to ResetWhirlpool Built-in Microwave Message "Press Cancel to Reset": Error Cleared by Cancel
4d424d42 questions
Why would a fan run too fast?

The control watches fan speed. An airflow restriction, the fan or the wiring can all push the reading out of range. We test each before suggesting a part.

Is a loud fan the same as 4d42?

Not always. Noise alone is not the code. 4d42 means the control saw a fan speed above what it expects. We measure the speed to confirm.

Can older built-in microwaves still be repaired for this?

Yes. Many are still in Houston homes. We compare repair cost with the unit and tell you plainly if a repair is not worth it.

Book a visit

Still seeing 4d42?

A technician diagnoses it on site and gives you the price in writing before any work starts.

(713) 589-6107