Error code reference

Lennox Heat Pump Error Code 1

Long Run Time-Compressor is running extremely long run cycles, indicating possible low charge, frozen evaporator coil, faulty metering device, dirty condenser coil, liquid line restriction, or thermostat malfunction.

SourceLennox XPG20 Heat Pump - Service ManualPage 14, Table 3

Lennox codes Lennox heat pump codes

Diagnostic procedure

The full 1 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

First diagnostic step

Check for low refrigerant charge, verify evaporator blower is running, check for frozen evaporator coil, check metering device, inspect condenser coil for dirt, check for liquid line restriction.

SourceLennox XPG20 Heat Pump - Service ManualPage 14, Table 3

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Where this code is documented

4 manuals in the MyPros+ library document this code for Lennox heat pump.

Models covered by the manuals that document this code

More models are covered than are listed here.

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The full 1 procedure

Where this code is documented

Models covered by the manuals that document this code

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