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Error code reference
Lennox Air Conditioner Error Code E434
Outdoor control has lost communications with the inverter for greater than 3 minutes (inverter code 53).
SourceLennox XC25 Series - Full Service Manual: Installation & Operationp. 33
Diagnostic procedure
The full E434 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
Check all electrical connections and check for proper main power to inverter.
SourceLennox Air Conditioner - Service Manual: Elite Series XC20p. 33
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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