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Error code reference
Whirlpool Microwave Error Code MV-4903
MW Relay failure (relay contact on ACU has welded closed).
SourceWhirlpool Microwave - Tech Sheet: Failure Codes & Service Procedures (W11365092)
Diagnostic procedure
The full MV-4903 procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
MyPros+ · DiagnosticsStep 1 preview
1
First diagnostic step
Unplug microwave oven or disconnect power. Check wiring to Relay 4903. Check to see if relay (4903 on ACU) contact has welded closed.
SourceWhirlpool Microwave - Tech Sheet: Failure Codes & Service Procedures (W11365092)
More steps, wiring diagram references, and verified part numbers
Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.
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Where this code is documented
1 manual in the MyPros+ library documents this code for Whirlpool microwave.
Models covered by the manuals that document this code
75,000+ service documents · 20,000+ error codes · 100+ brands
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