Lennox Air Conditioning

This error signifies a problem with the EEPROM (memory chip) within the MMDB indoor unit. This chip stores important operational settings.

For MMDB indoor units: This error means the indoor and outdoor units cannot communicate. This prevents the system from operating correctly.

For MMDB indoor units: This error indicates an issue with the indoor fan's speed regulation. The fan might be operating at an incorrect speed or not at all.

The indoor unit's return air temperature sensor (T1) is malfunctioning. This sensor measures the temperature of the air entering the indoor unit.

This code indicates a problem with the indoor coil temperature sensor (T2). This sensor measures the temperature of the indoor coil.

This error code indicates a problem with the indoor unit's EEPROM on specific MMDB models. The EEPROM stores essential operating data.

The system has detected a low level of refrigerant. This can lead to reduced cooling or heating efficiency and potential system damage.

The outdoor unit's DC fan motor is not operating correctly, or its speed is not being properly controlled. This can affect heat exchange.

The outdoor temperature sensor is reporting an error. This sensor is vital for the system to adjust its operation based on outside conditions.

An error has been detected in the outdoor unit's EEPROM (memory). This component stores critical system settings and data.

The temperature sensor for the condenser coil (T3) is malfunctioning. This sensor monitors the temperature of the outdoor coil.

The outdoor ambient temperature sensor (T4) is malfunctioning. This sensor provides crucial data about the outside air temperature.

The temperature sensor (TP) for the compressor discharge line is either not connected (open circuit) or has a short circuit. This prevents accurate temperature readings.

The temperature sensor monitoring the outdoor unit's Intelligent Power Module (IPM) is malfunctioning. The IPM is critical for power conversion.

The T2B sensor in the outdoor unit is experiencing an error. This sensor typically measures the temperature at the outlet of the outdoor coil.

The sensor monitoring the temperature of the refrigerant pipes is malfunctioning. This provides data on refrigerant flow and temperature.

The outdoor unit's DC fan motor is drawing too much current, indicating a potential overload or internal motor issue.

This error indicates a phase issue with the outdoor DC fan motor, suggesting a problem with the motor's internal circuitry or power delivery.

For ducted units only: The condensate drain system is overwhelmed or blocked, causing the water level to become too high. This is a safety measure to prevent water damage.

This error indicates that the indoor and outdoor units cannot communicate properly. This is essential for the system to operate.

The outdoor unit has detected that the current flowing through its components is higher than the safe limit. This can indicate a mechanical or electrical issue.

The outdoor ambient temperature sensor (T4) is not functioning correctly. This sensor provides data about the outside air temperature to the system.

The system has detected an issue with the outdoor coil temperature sensor (T3). This sensor helps regulate the unit's performance based on outdoor conditions.

This error indicates a malfunction with the compressor discharge temperature sensor (T5). This sensor monitors the temperature at the compressor's outlet.

An error has been detected in the outdoor unit's EEPROM (Electrically Erasable Programmable Read-Only Memory). This memory stores important configuration data.

The system is reporting an issue with the speed control of the outdoor unit's fan. The fan may not be running at the correct speed or may not be running at all.

This error code signifies a problem with the indoor coil outlet temperature sensor (T2B). This sensor measures the temperature of the refrigerant leaving the indoor coil.

The system has detected that the installed indoor unit(s) and outdoor unit are not compatible with each other based on their rated capacities.

The Intelligent Power Module (IPM) in the inverter has reported an error. The IPM is crucial for controlling the compressor's speed.

The unit has detected that the input voltage is either too high or too low. This protection feature prevents damage to the system's components.

The compressor's top temperature has exceeded safe operating limits. This can occur due to operational strain or inadequate cooling.

The system has shut down because the outdoor temperature is too low for safe operation. This prevents damage during cold conditions.

There is an error related to the compressor's drive system. This indicates a problem with how the compressor is being powered or controlled.

The system's high or low pressure switch has been activated, indicating a potentially unsafe pressure level within the refrigerant system.

There is an error with the temperature sensor monitoring the Insulated Gate Bipolar Transistor (IGBT) in the outdoor unit. The IGBT is a critical component for power switching.

The system has activated protection for the Inverter module (IPM). This component is essential for controlling the compressor's speed and power delivery.

The compressor's top temperature has exceeded its safe operating limit. This indicates potential overheating.

The temperature at the compressor's discharge line is too high. This is a protective shutdown to prevent damage.

The outdoor unit is experiencing an over-current condition. This means too much electrical current is flowing through a component, triggering a safety shutdown.

The condenser coil in the outdoor unit has reached an excessively high temperature, triggering a protective shutdown.

Protection has been activated for the Power Factor Correction (PFC) module. This module helps regulate power input to the unit.

The system has entered a low temperature protection mode for the outdoor unit. This typically occurs when ambient temperatures are too low for operation.

The outdoor unit has detected that the AC voltage supplied to it is too low, potentially causing operational issues or damage.

The DC bus voltage on the outdoor unit's main control board has become excessively high, triggering a protective shutdown.

This code indicates high DC bus voltage on the main control board, possibly accompanied by a Machine Check Error (MCE). This suggests a critical electrical fault.

The refrigerant system pressure has risen too high, activating a safety protection. This can be due to various factors hindering proper refrigerant flow.

The refrigerant system pressure has dropped too low, triggering a protective shutdown. This often indicates a lack of refrigerant or a restriction.

There is a communication failure between the main control chip and the compressor driver chip in the outdoor unit.

The outdoor unit's compressor is failing to start. This could be due to electrical issues or a problem with the compressor itself.

The outdoor compressor is experiencing a lack of phase issue, meaning one or more of the electrical phases required for its operation are missing or unstable.

The outdoor unit's compressor or fan is detected as having zero speed when it should be running, triggering a protection.

There is a failure in the Infrared (IR) chip drive system of the outdoor unit. This chip is often involved in communication or control functions.

The speed of the compressor is not being regulated properly and has gone outside of its expected operating range.

The compressor is drawing excessive current, leading to an over-current protection trigger. This can damage the compressor if not addressed.

The system has detected condensation on the refrigerant pipes, indicating potential issues like insufficient insulation or improper operation.

The evaporator coil has reached a high temperature, activating a protection mechanism. This is more common in heating mode.

The evaporator coil has reached a low temperature, potentially leading to freezing. This protection prevents ice buildup.