Model reference
Lennox 10J42
Heat Pump
2 documents23 error codes2 service modes
Available documentation
Service Manual
- XP16 Series Service Literature24 pg
- XPG20 Series Service Literature36 pg
MyPros+ Max
Diagnose your Lennox 10J42.
- Step-by-step diagnostics from the service manual
- Test values, resistance specs, and wiring references
- Verified part numbers when replacement is needed
Start diagnosing
$29/month · Cancel anytime · Or $9.95 3-day pass · Plus applicable tax
Error codes (23)
CodeMeaning
1Long Run Time2System Pressure Trip or Discharge Sensor Fault3Short Cycling4Locked Rotor5Open Circuit6Open Start Circuit7Open Run Circuit8Welded Contactor9Low VoltageDS2:Alternating FAST Flash / DS1:Alternating FAST FlashCoil sensor problemDS2:Alternating SLOW Flash / DS1:Alternating SLOW Flash5-minute anti-short cycle delay due to initial power up, safety trip, or end of…DS2:FAST Flash / DS1:OFFDischarge sensor lockoutDS2:FAST Flash / DS1:ONDischarge line temperature lockoutDS2:OFF / DS1:FAST FlashDischarge sensor faultDS2:OFF / DS1:OFFNo power (24V) to board terminals R & C or board failure.DS2:OFF / DS1:ONLow pressure lockoutDS2:OFF / DS1:SLOW FlashLow pressure faultDS2:ON / DS1:OFFHigh pressure lockoutDS2:ON / DS1:ONCircuit board failureDS2:Simultaneous FAST Flash / DS1:Simultaneous FAST FlashAmbient sensor problemDS2:Simultaneous SLOW Flash / DS1:Simultaneous SLOW FlashNormal operationDS2:SLOW Flash / DS1:OFFHigh pressure faultDS2:SLOW Flash / DS1:ONDischarge line temperature faultService modes (2)
- Compressor Modulation Operational Check["Turn main power OFF to outdoor unit.","Adjust room thermostat set point above (heating) or below…
- Defrost Board Test Mode["Ensure Y1 input is active (ON) and the O room thermostat terminal into board is inactive (heating…
Full entry steps, exit procedures, and test sequences are available in Max.
75,000+ service documents · 20,000+ error codes · 100+ brands
Get Started$29/month · Cancel anytime · Or $9.95 3-day pass · Plus applicable tax