Mitsubishi Heavy Industries Air Conditioners

The unit detects a faulty power source or improper wiring of power/signal lines. This occurs if communication signals are not detected within 10 seconds after power-on.

The system cannot receive signals from the wired remote control for 35 seconds. This indicates a problem with the remote control wiring, the remote control unit, or the indoor PCB.

The system's high-pressure control has activated during cooling operation and caused the compressor to stop. This indicates issues with refrigerant levels, closed service valves, or inefficient heat exchange.

The system detects that the outdoor heat exchanger sensor wire is disconnected. This prevents the unit from accurately monitoring temperatures and can lead to incorrect operation.

The outdoor heat exchanger sensor is reporting abnormal readings, such as –55°C or lower (or higher) repeatedly, which affects the unit's ability to operate correctly.

The outdoor air temperature sensor is reporting abnormal readings, such as –55°C or lower (or higher) continuously, which impacts the unit's control and efficiency.

The discharge pipe sensor is reporting abnormal readings (its value exceeds the set limit) or its wire is disconnected, leading to an anomalous stop of the unit.

The compressor has overheated to 110°C, triggering a protective shutdown. This usually indicates an issue with the refrigerant flow, the electronic expansion valve, or the compressor itself.

The outdoor unit's fan motor is detected to be running at 75 min-1 or lower for 30 seconds or longer, indicating a malfunction or obstruction preventing proper fan operation.

The compressor has stopped due to a 'current cut', potentially after failing to start multiple times in succession. This suggests problems with compressor wiring, the power transistor, or the compressor itself.

The unit detected a voltage drop during operation or the compressor command speed was lower than 32 rps for 60 minutes, leading to the activation of protective control.

The compressor rotor has locked after starting, causing the compressor to stop. This indicates a mechanical issue with the compressor itself.

Faulty connection lines between the indoor and outdoor units are detected. This can lead to communication errors or improper operation of the system.

A serial transmission error is detected, meaning communication signals between units are not correctly detected for 7 minutes and 35 seconds. This is a critical communication fault.

The indoor unit's fan motor is detected to be running at 300 min-1 or lower speed while the air conditioner is operating and the fan motor is commanded to be ON.

The indoor heat exchanger sensor is reporting abnormal readings, its wire is disconnected, broken, or short-circuited, leading to an anomalous stop of the unit.

There is an issue with the condensate drain system, detected by the float switch being open continuously for 3 seconds or a disconnected float switch connector/wire.

The anti-frost control has activated, causing the compressor to stop during cooling operation. This is often a normal protective function when the outdoor temperature drops very low (e.g., –28°C or lower for 40 minutes during heating operation).

The anti-condensation prevention control is operating. This typically occurs in conditions of high humidity to prevent moisture buildup inside the unit or ductwork.

The system's high-pressure control has activated during heating operation and caused the compressor to stop. This indicates issues with refrigerant levels, closed service valves, or inefficient heat exchange during heating.

The remote control displays E1, and the indoor unit's red LED flashes three times (while the green LED keeps flashing). This indicates a problem with the remote control communication circuit.

Error code E1, indicated by the indoor unit's red LED flashing three times, means there is an open circuit in the remote controller's wiring. This prevents proper communication.

Error E2, shown by a single flash of the indoor unit's red LED, indicates that an indoor unit's address is duplicated or more than 49 indoor units are connected to the network, which exceeds the maximum limit.

When both the indoor and outdoor unit's red LEDs flash twice, it signals a communication error between the outdoor and indoor units. This prevents the system from operating correctly.

Error E3, indicated by the indoor unit's red LED flashing twice, means the outdoor unit's address setting is incorrect. Proper addressing is essential for system communication.

Error E3, with the indoor unit's red LED flashing twice and the outdoor unit's red LED staying off, suggests a failure in the outdoor unit's control PCB or faulty inverter components.

Normal communication between the indoor and outdoor units has been interrupted for more than 2 minutes while the unit is operating. This could be due to issues with wiring or temporary electrical noise.

The remote control displays E5, and the indoor unit's red LED flashes twice (while the green LED keeps flashing). This indicates a communication error between the indoor and outdoor units during operation.

Error E5, shown by the indoor unit's red LED flashing twice, indicates a failure in the outdoor unit's microcomputer. This critical component manages the outdoor unit's operations.

The remote control displays E6, and the indoor unit's red LED flashes once (while the green LED keeps flashing). This indicates an issue with the indoor heat exchanger temperature sensor.

Error E6, indicated by a single flash of the indoor unit's red LED, means the indoor unit's heat exchanger sensor (ThIR) is defective, either due to an open or closed circuit, or has a poor connection to the indoor PCB.

The remote control displays E7, and the indoor unit's red LED flashes once (while the green LED keeps flashing). This indicates an issue with the indoor return air temperature sensor.

Error E7, signaled by a single flash of the indoor unit's red LED, indicates a defective indoor return air sensor (ThIA) or a poor connection. It can also be triggered by an unusually high temperature in the indoor heat exchanger during heating, suggesting an overload.

The remote control displays E8, and the indoor unit's red LED flashes once (while the green LED keeps flashing). This indicates the unit is experiencing an overload during heating operation, leading to abnormally high indoor heat exchanger temperatures.

Error E8, indicated by one flash of the indoor unit's red LED, can point to several issues: a closed circuit in the indoor heat exchanger sensor (ThIR), a fault with the drain motor (DM), condensate remaining in the drain tray due to blockage, or a float switch stuck in a high position.

The remote control displays E9, and the indoor unit's red LED flashes once (while the green LED keeps flashing). This indicates a problem with the unit's drainage system.

Error E9, indicated by a single flash of the indoor unit's red LED, means there's a defective input circuit for the float switch or a defective output circuit for the drain motor on the indoor PCB.

The remote control displays E10. This indicates that more than 17 indoor units are being controlled by a single remote control in a multi-unit setup, exceeding the system's limit.

This error occurs when the indoor unit address was incorrectly set using the 'Master IU address set' function on the remote control. Addresses for this system should be set directly via DIP switches on the indoor unit PCB.

The remote control displays E11, and the indoor unit's red and green LEDs both keep flashing. This indicates an error in the address settings of the indoor units.

Error E12, indicated by a single flash of the indoor unit's red LED, signals an addressing issue. This can happen if units retain factory addresses (48 or 49), if a unit isn't set to 49 during auto-addressing, or if auto-addressing isn't compatible with the system type (only single KX2 systems).

Error E14, indicated by three flashes of the indoor unit's red LED, points to problems in a master/slave system setup. This could be incorrect SW5 settings on the indoor PCB, wrong control wiring (XYZ), or an open circuit in the control wiring between units.

Error E16 indicates a faulty indoor fan motor. The system's LEDs may appear in their normal operational state, making the fault harder to diagnose without the error code.

The remote control displays E16, and the indoor unit's red LED flashes once or twice (while the green LED keeps flashing). This indicates an issue with the indoor fan motor.

Error E16, indicated by a single flash of the indoor unit's red LED, means there is a faulty indoor fan motor. This prevents proper airflow and system operation.

The remote control displays E19, and the indoor unit's red LED flashes once (while the green LED keeps flashing). This indicates an improper operation mode setting within the indoor unit's control PCB.

The remote control displays E20, and the indoor unit's red LED flashes once or twice (while the green LED keeps flashing). This indicates an anomaly with the indoor fan motor's rotation speed.

The remote control displays E28 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates a problem with the remote control's temperature sensor.

Error E30, indicated by a single flash of the outdoor unit's red LED, means there is a connection error between the indoor and outdoor units. This prevents proper system operation.

Error E31, indicated by one flash of the outdoor unit's red LED, points to an addressing problem. This can be a duplicated indoor unit address (U00-U47) or an incorrect setting for the outdoor unit's address.

Error E32, indicated by a single flash of the outdoor unit's red LED, signals an issue with the mains power phasing. This means two phases might need to be swapped, or the L2 phase has been detected as open.

Error E34, shown by one flash of the outdoor unit's red LED, indicates an abnormally low current or no current detected on the L3 phase, or an open phase on L3 (secondary side of the contactor).

Error E35, signaled by a single flash of the outdoor unit's red LED, means the outdoor unit's heat exchanger sensor (ThOR) is defective (open or closed circuit), has a poor connection, or indicates excessively high pressure during cooling.

The remote control keeps flashing (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates the outdoor unit is experiencing an overload during cooling operation, specifically a higher outdoor heat exchanger temperature.

The remote control displays E36 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates an error with the discharge pipe temperature, likely due to abnormally high temperatures.

Error E36, shown by a single flash of the outdoor unit's red LED, indicates an abnormally high discharge temperature. This can be caused by insufficient refrigerant or a defective compressor discharge temperature sensor (ThOD).

The remote control displays E37 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates a problem with the outdoor heat exchanger temperature sensor.

Error E37, indicated by one flash of the outdoor unit's red LED, signifies a general fault with an outdoor unit heat exchanger sensor (ThOR). This could be due to a defective sensor or a poor connection.

Error E37-1, identified by one flash of the outdoor unit's red LED, indicates a failure of the outdoor heat exchanger thermistor Tho-R1. This sensor is crucial for temperature readings.

Error E37-2, identified by two flashes of the outdoor unit's red LED, indicates a failure of the outdoor heat exchanger thermistor Tho-R2. This sensor is crucial for temperature readings.

Error E37-3, identified by three flashes of the outdoor unit's red LED, indicates a failure of the outdoor heat exchanger thermistor Tho-R3. This sensor is crucial for temperature readings.

Error E37-4, identified by four flashes of the outdoor unit's red LED, indicates a failure of the outdoor heat exchanger thermistor Tho-R4. This sensor is crucial for temperature readings.

Error E37-5, identified by five flashes of the outdoor unit's red LED, indicates a failure of the outdoor heat exchanger thermistor Tho-SC. This sensor is crucial for temperature readings.

Error E37-6, identified by six flashes of the outdoor unit's red LED, indicates a failure of the outdoor heat exchanger thermistor Tho-H. This sensor is crucial for temperature readings.

The remote control displays E38 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates a problem with the outdoor air temperature sensor.

Error E38, indicated by one flash of the outdoor unit's red LED, means the outside air temperature sensor (ThoA) is defective (open circuit) or has a poor connection to the outdoor unit PCB.

The remote control displays E39 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates a problem with the discharge pipe temperature sensor.

Error E39, indicated by one flash of the outdoor unit's red LED, means the compressor discharge temperature sensor (ThOD) is defective (open circuit) or has a poor connection to the outdoor unit PCB.

The remote control displays E40 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates that the service valve on the gas side is closed.

Error E40, signaled by one flash of the outdoor unit's red LED, means the high-pressure switch (63H or 63H1) has tripped. This can be due to system overcharging with refrigerant, a shut service valve, or insufficient airflow over the condenser coil.

Error E41, indicated by one flash of the outdoor unit's red LED, means the power transistor for the inverter has overheated. This can damage the inverter and disrupt system operation.

The remote control displays E42 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates a 'current cut' event, likely due to anomalous compressor over-current or a service valve closing operation.

Error E42, indicated by one flash of the outdoor unit's red LED, means an abnormally high current has been detected in the compressor. This is a serious electrical fault that can damage the compressor.

Error E43, indicated by one flash of the outdoor unit's red LED, means the maximum allowed number of indoor units connected to a single outdoor unit has been exceeded.

Error E45, shown by one flash of the outdoor unit's red LED, indicates a transmission error between the inverter and the outdoor unit PCB. This could be due to a loose connection of the CnI cable.

Error E46 indicates a conflict in address settings within the system. This can occur if automatic, manual, and remote control addresses are mixed on a single network, causing confusion for the system.

The remote control displays E47 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates an error related to the active filter voltage on the outdoor unit control PCB.

The converter voltage has exceeded the target voltage (3 times within 20 minutes) or fallen below DC210V (1 time within 5 seconds after power ON). If overvoltage (DC higher than 400V) occurs, the Indoor Red LED will flash once.

Error E47, indicated by one flash of the outdoor unit's red LED, means the inverter has detected an over-voltage condition. This can be caused by unstable power supply.

The remote control displays E48 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates an anomaly with the outdoor fan motor rotation. The system stops if the fan speed drops below 75 min⁻¹ for 30 seconds, and may restart after 3 minutes. If this anomaly occurs 3 times within 60 minutes after the initial detection, the error is permanent.

Error E48, indicated by one flash of the outdoor unit's red LED, signals a fault with the DC outdoor fan motor. This fan is crucial for heat exchange in the outdoor unit.

Error E49, indicated by one flash of the outdoor unit's red LED, signals either a low pressure fault, low voltage detected in the system, or a fault with the inverter PCB. All these can prevent proper operation.

The power transistor primary current has exceeded its safe limit for 3 seconds, causing the compressor to stop. This indicates a problem with the power transistor assembly on the outdoor unit.

Error E51, shown by one or two flashes of the outdoor unit's red LED, means the power transistor has overheated. This component is part of the inverter circuit and overheating can lead to system shutdown.

Error E53, indicated by one flash of the outdoor unit's red LED, points to a disconnected suction pipe thermistor (Tho-S) or a disconnected/output error with the low pressure sensor (PSL). Both are critical for system monitoring.

Error E54, indicated by two flashes of the outdoor unit's red LED, points to a general pressure sensor issue. This could be related to either low or high pressure sensors.

Error E54-1, indicated by one flash of the outdoor unit's red LED, signifies a disconnection or output error from the low pressure sensor (PSL). This sensor monitors system pressure.

Error E54-2, indicated by two flashes of the outdoor unit's red LED, signifies a disconnection or output error from the high pressure sensor (PSH). This sensor monitors system pressure.

Error E55, indicated by one flash of the outdoor unit's red LED, means the compressor under dome thermistor is disconnected. This sensor monitors the compressor's temperature for safe operation.

Error E56, indicated by one flash of the outdoor unit's red LED, means the power transistor thermistor is either faulty or disconnected (specifically for FDCVA151-251 models). This sensor monitors power transistor temperature.

The remote control displays E57 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates either an insufficient amount of refrigerant in the system or that a service valve is closed.

Error E57, indicated by one flash of the outdoor unit's red LED, means there is a refrigerant leak or a shortage of refrigerant in the system (specifically for FDCVA151-251 models).

The remote control displays E58 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates a 'current safe stop' due to overload operation, overcharge, or compressor locking. The system has stopped to protect itself.

The system initiated a 'current safe stop' during operation, specifically when the compressor speed was 30 rps or under. This suggests problems with refrigerant levels, airflow, or key sensors.

The remote control displays E59 (while the indoor unit's green LED keeps flashing and red LED stays off). This indicates a failure of the compressor to start properly.

Error E59, indicated by 1 to 5 flashes of the outdoor unit's red LED, means there's an error during the compressor start-up sequence. This can prevent the unit from heating or cooling.

The remote control displays E60 (while the indoor unit's green LED stays off and red LED keeps flashing). This indicates a compressor rotor lock error, meaning the compressor's rotor is unable to rotate. The system attempts to detect rotor position, and if it fails again, the compressor stops.

Error E60, shown by one or two flashes of the outdoor unit's red LED, means there's a compressor position detection error. This sensor helps the system understand the compressor's rotation.

Error E63, indicated by one flash of the outdoor unit's red LED, means an emergency stop has been activated for an indoor unit. This could be due to a safety mechanism or system malfunction.

The earth leakage breaker has tripped, cutting power to the unit. This often occurs due to low insulation resistance in the compressor or an improper breaker type for inverter units.

The indoor unit's green LED is either continuously off or continuously on, suggesting a problem with the indoor unit's circuit board or central processing unit (CPU).

The indoor unit's red LED flashes twice, signaling that there is no mains power reaching the outdoor unit. This could be due to the power being off or a power failure.

Both the red and green LEDs on the indoor unit are either continuously off or continuously on. This pattern points to a failure of the indoor unit's circuit board or its central processing unit (CPU).

The LCD display on the remote controller continuously flashes or is off, and the outdoor unit's red LED flashes twice. This indicates an open circuit or poor connection in the interconnecting wiring between the indoor and outdoor units.

The unit has no LED indication because it is not receiving mains power. This could be due to a power outage or a broken L phase wire.

The remote control shows no display, and both the red and green LEDs on the indoor unit are off. This indicates a problem with the indoor unit's power source.

The outdoor unit's red LED flashes three times, indicating an issue with the remote controller wiring. This can be caused by reversed connections or a broken wire.

The indoor unit's red LED keeps flashing and the green LED stays off. This indicates a communication error within an optional control unit, such as SC-SL2NA-E or SC-SL4-AE/BE.

The system is detecting a communication error when first powered on. This message may appear if the main power breaker is repeatedly turned on and off too quickly.

The remote control displays 'WAIT' or 'INSPECT I/U'. This indicates a general communication error between indoor and outdoor units, or between remote controls, potentially due to wiring issues or incorrect settings.