HVAC, Appliance, CNC, and VFD Error Code Repair Guides

Browse repair guides for HVAC, appliances, refrigeration, CNC alarms, VFD faults, generators, boilers, water heaters, and commercial equipment.

• Lennox Error Code 411 Ignition Proving Fault

  Updated: 16 Sep, 2026

  Lennox 411 guide for ignition proving faults, flame-sensor signal, igniter checks, gas-pressure symptoms, lockout resets, and service limits.

• Mitsubishi Mini Split E1 Indoor Thermistor Fault

  Updated: 16 Sep, 2026

  Mitsubishi E1 guide for indoor room thermistor faults, sensor resistance checks, wiring issues, MSZ/MXZ units, and control-board decisions.

• Navien Error Code E012 Flame Loss

  Updated: 16 Sep, 2026

  Navien E012 guide for flame loss during operation, gas-pressure drops, vent blockage, condensate backups, flame sensing, and pro repair limits.

• Rheem RA14 Heat Pump Error Codes

  Updated: 16 Sep, 2026

  Rheem RA14 heat-pump flash-code guide for pressure trips, thermostat circuits, defrost faults, refrigerant warnings, and service decisions.