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Error code reference
Lennox Air Conditioner Error Code E412
The outdoor unit high pressure switch has opened indicating unit pressure is above the upper limit.
SourceLennox XC25 Series - Full Service Manual: Installation & Operationp. 31
Diagnostic procedure
The full E412 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
Confirm system is properly charged with refrigerant. Check for clogged TXV, blockage to indoor unit blower motor, clogged refrigerant filter. Confirm outdoor unit is clean.
SourceLennox Air Conditioner - Service Manual: Elite Series XC20p. 31
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
2 manuals in the MyPros+ library document this code for Lennox air conditioner.
Models covered by the manuals that document this code
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