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Error code reference
Denso Air Conditioner Error Code E21
Power device damage abnormality: compressor startup current/voltage at or below specified value detected.
SourceDENSO CM 25 Air Conditioner - Full Service Manualp. 45, 54
Diagnostic procedure
The full E21 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
Replace the relay board, then initialize the fan motor.
SourceDENSO CM 25 Air Conditioner - Full Service Manualp. 45, 54
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 Denso air conditioner.
Models covered by the manuals that document this code
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