Mitsubishi Electric Mitsubishi FR-D700 Inverter

One or more units (indoor or outdoor) are still addressed at 48 or 49 (factory setting). This prevents auto-addressing, which is only possible on a single KX2 system, if one or more units (either indoor or outdoor) are not set at 49.

This indicates an incorrect setting of DIP switches (SWS) on the indoor unit PCB when configuring a master/slave system. It also points to incorrect control wiring or an open circuit in the control wiring between master and slave units.

The indoor fan motor is faulty, preventing proper air circulation. This can lead to inefficient cooling/heating or system shutdown.

The sensor within the remote controller has failed, leading to incorrect temperature or operational readings. This affects the indoor unit's ability to control room temperature accurately.

This error indicates a problem with the connection or communication between the indoor and outdoor units. It prevents proper system operation and coordination.

There is a duplication of an indoor unit address number within the U00-U47 range, or an outdoor unit address setting error has occurred. This conflict prevents proper system communication and unit identification.

The anti-phase device has detected that two phases of the mains power need to be swapped, indicating a phase reversal. Alternatively, the L2 phase of the mains power (primary side of contactor) has been detected as open, leading to unbalanced power.

Abnormally low current or no current has been detected by the current transformer (CT) on L3. This indicates an open phase condition detected at L3 (secondary side of contactor), which can prevent the compressor from operating correctly.

The outdoor unit heat exchanger sensor (ThOR) is defective, indicated by an open or closed circuit resistance, or by a poor connection of the sensor connector on the outdoor unit PCB. This can also be caused by high pressure in the cooling system, impacting heat exchange.

The compressor discharge temperature is abnormally high. This can be caused by insufficient refrigerant, a defective compressor discharge temperature sensor (THOD), or other system issues leading to compressor overheating and potential damage.

The outdoor unit heat exchanger sensor (ThOR) is defective (open circuit resistance) or has a poor connection on the outdoor unit PCB. This error may also specify which particular thermistor (Tho-R1 to Tho-R6) has failed, leading to inaccurate temperature readings.

The outside air temperature sensor (ThoA) is defective (open circuit resistance) or has a poor connection on the outdoor unit PCB. This compromises the system's ability to accurately sense ambient conditions and adjust operation.

The compressor discharge temperature sensor (ThOD) is defective (open circuit resistance) or has a poor connection on the outdoor unit PCB. This can lead to incorrect discharge temperature monitoring, potentially causing compressor damage.

The high-pressure switch (B3H or 63H1) has tripped. This can be caused by a system overcharged with refrigerant, one or more service valves being shut, or insufficient airflow over the condenser coil, all leading to dangerously high system pressures.

The power transistor for the inverter has overheated, indicating excessive heat generation, potentially due to a fault or overload condition. This poses a risk to the inverter module's longevity.

Abnormally high current has been detected in the compressor, indicating a potential electrical or mechanical fault with the compressor, or system overload. This can lead to compressor failure if not addressed.

The maximum allowed number of indoor units connected to one outdoor unit has been exceeded, or an outdoor unit has reached its capacity limit. This leads to system communication issues and operational faults.

A transmission error has occurred between the inverter and the outdoor unit PCB, possibly due to a loose connection at the 'Cal' terminal. This disrupts critical communication and control signals.

There is a conflict of address settings, where a combination of automatic, manual, or remote control addresses coexist on the same network. This prevents proper system addressing and communication.

The inverter has detected an overvoltage condition, which could be due to an unstable power supply or a malfunction within the inverter itself. This protects the inverter components from damage.

There is a fault with the DC outdoor fan motor, which could prevent proper heat exchange in the outdoor unit. This leads to inefficient operation and potential system overheating.

This fault indicates a low pressure condition, low voltage detected within the system, or an inverter PCB fault. The manual lists these three distinct sub-causes for E49, any of which can lead to system malfunction.

The power transistor has overheated, indicating excessive heat generation, potentially due to a fault or overload condition. This protects the inverter from damage.

The suction pipe thermistor (Tho-S) is disconnected, which will prevent accurate temperature readings for the suction line. This compromises the system's ability to regulate superheat and optimize refrigerant flow.

This error indicates a disconnection or output error with either the low-pressure sensor (PSL) (E54-1) or the high-pressure sensor (PSH) (E54-2). This prevents accurate pressure monitoring, jeopardizing system safety and control.

The thermistor located under the compressor dome is disconnected, which will prevent critical temperature monitoring of the compressor shell. This can lead to undetected compressor overheating and failure.

The power transistor thermistor is faulty or disconnected (specific to FDCVA151-251 models), impacting temperature monitoring of the power transistors. This can lead to inverter damage from overheating.

This indicates a refrigerant leak or shortage of refrigerant (specific to FDCVA151-251 models), leading to insufficient cooling or heating performance. A low refrigerant charge can cause compressor overheating and damage.

The compressor has failed to start properly, which can be due to electrical issues, mechanical binding, or control problems. This prevents the system from generating cooling or heating capacity.

An error has occurred in detecting the compressor's rotational position, which is critical for proper inverter control. This can prevent the compressor from starting or running smoothly, leading to system shutdown.

The indoor unit has initiated an emergency stop, indicating a critical safety or operational fault. This requires immediate attention to prevent further damage or unsafe conditions.