Lennox EL18KSLV Series Outdoor Units

This error means the EEPROM chip on the main control board is damaged, has incorrect data, or there's a problem with its related circuits. The system cannot read or write data to this chip.

There is an electrical failure with the sensor that measures the outdoor coil temperature during defrost cycles. This sensor is connected to the PCB.

There is an electrical failure with the sensor that measures the suction gas temperature entering the compressor. This sensor is connected to the PCB.

There is an electrical failure with the sensor that measures the compressor hot gas discharge line temperature. This sensor is connected to the PCB.

There is an electrical failure with the sensor that measures the outdoor ambient air temperature. This sensor is connected to the PCB.

This error code suggests the system may be low on refrigerant. Check the system's refrigerant charge.

The 4-way valve is not functioning correctly to direct hot gas to the proper coil. This affects heating and cooling operation.

Loss of synchronization between the compressor windings (U, V, W) occurred during speed changes. This can be caused by unstable power, internal compressor faults, or wiring issues.

The Inverter Power Module (IPM) has detected excessive current or has failed. This can happen due to overcharging, a dirty outdoor coil, or restrictions in the refrigeration circuit.

Low voltage has been detected by the compressor drive module. This could be due to a low AC input voltage or a low DC bus voltage.

The compressor drive module is overheating. This is detected by a sensor on the module's heat sink. Causes include refrigerant overcharge or a blocked coil.

The compressor did not start when a call for operation occurred. This requires a check of the compressor's starting ability.

The main control board's software has detected that the compressor current is too high, based on EEPROM settings.

The compressor drive module has experienced a power supply failure or a reset. This often happens with low line voltage conditions.

The compressor module's inverter side has detected a momentary overcurrent in the compressor.

There is an electrical failure with the sensor measuring the outdoor coil's condensing temperature. The sensor is connected to the PCB.

The main control board and the IPM are not communicating. This could be due to wiring issues or a problem with one of the boards.

The 4-way valve is responsible for directing hot gas. If it fails to shift correctly, temperature sensors will detect a problem and trigger an error code.

The high pressure switch has opened. This indicates excessively high system pressure.

The low pressure switch has opened. This indicates excessively low system pressure.

The system is operating at excessive refrigerant pressure. This could be due to overcharge, a dirty coil, or a restriction.

The system pressure is too low. This can be caused by low refrigerant charge, restrictions, or a low indoor load.

The temperature sensor on the compressor driver module's heat sink is reporting an abnormal temperature, outside the range of -25°C to 150°C.

The IPM is preventing the compressor from running due to an overload condition. This can be caused by low building power, system restrictions, or refrigerant overcharge.

There is an electrical failure with the sensor that measures the system's refrigerant pressure. This sensor is connected to the PCB.

Excessive current has been detected on the AC input by the compressor drive module or the input current exceeds the main board's setting.

The temperature of the compressor's hot gas discharge is too high. The system may try to reduce compressor speed or adjust fan speed to correct this.

The outdoor fan motor is not running or is experiencing an issue. This fault is detected quickly by the control board.

The Electronic Expansion Valve (EEV) may not be functioning correctly if its connector is loose or its resistance is outside the specified limits.

During cooling mode, there should be a 'W' signal present. If it's absent, it indicates a potential issue with the thermostat or unit wiring.

A pattern error has occurred, indicated by a 'w' during cooling mode. This suggests a problem with the thermostat or unit wiring.

A pressure sensor has been detected as having an open or short circuit, indicating a malfunction.

The system detected that the outdoor defrosting temperature sensor is reading outside its expected range, or it's not sending a signal (open or short circuit).

The system detected that the suction temperature sensor is reading outside its expected range, or it's not sending a signal (open or short circuit).

The system detected that the outdoor ambient temperature sensor is reading outside its expected range, or it's not sending a signal (open or short circuit).

The system detected that the discharging temperature sensor is reading outside its expected range, or it's not sending a signal (open or short circuit).

The compressor motor is out of sync. This can be caused by overload, fluctuating loads, issues with the current sensor circuit, or a missing inverter gate drive signal.

The drive module has detected that the compressor failed to start. This could be due to power supply issues, wiring problems, a faulty power module, a bad compressor, or system overload.

The current going into the compressor drive module is exceeding the normal limits (30A for 48&60k models, 18A for 36k, or 15A for 24k).

The high pressure switch circuit has been detected as open for 30 seconds after 5 minutes of compressor run time. This indicates a potential issue with system pressure or the switch itself.

The low pressure switch circuit has been detected as open for 60 seconds (after 5 minutes of compressor run time) or for 30 seconds during standby. This suggests a problem with system pressure or the switch.

The compressor discharge temperature has exceeded 115°C. The error should clear within 3 minutes if the temperature drops below this threshold.

The DC fan motor is damaged, not connected, or the related circuit is broken. The error will lock if it occurs 4 times within 60 minutes.