Mitsubishi Electric FR-D700

A voltage (or current) has been input to terminal 4 when the setting in Pr. 267 Terminal 4 input selection and the physical voltage/current input switch on the inverter are mismatched. This incorrect input configuration can lead to erroneous frequency commands, unstable operation, or potentially damage the analog input circuit if not corrected.

The analog input bias and gain calibration values (C3, C4, C6, C7) have been set too close, potentially causing instability, inaccuracy, or an invalid range in analog input readings. This can lead to incorrect frequency commands or control signals, affecting system performance. The inverter output is not shut off.

An error has occurred within the inverter's Central Processing Unit (CPU) or its associated peripheral circuits. This is a critical internal hardware or software issue, potentially leading to a complete loss of control and unpredictable inverter behavior. Continued operation or neglect may result in further hardware damage or system unresponsiveness.

This fault code signifies a detected malfunction within the inverter's internal safety circuit, specifically indicating an issue related to the CPU's safety monitoring functions. When triggered, it causes the inverter to shut off its output to maintain a safe state and prevent motor operation.

An excessive current condition has been detected while the inverter is accelerating the motor. This can be caused by an abnormally high load, a short circuit between phases, or a ground fault on the inverter's output side, potentially leading to damage if not resolved.

This fault code indicates a detected malfunction within the inverter's internal safety circuit. When active, it causes the inverter to shut off its output to ensure a safe state, preventing drive operation. This is a critical internal error.

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.

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.

The cumulative thermal value of the electronic thermal O/L relay has reached 85% or higher of the Pr. 9 (Electronic thermal O/L relay) setting. This indicates that the motor or inverter is approaching its thermal overload limit. Continuing operation without intervention will almost certainly lead to an electronic thermal overload trip, shutting down the inverter.

The external thermal relay connected to the OH signal has been activated. This indicates that the motor or connected equipment is experiencing an overload condition, potentially causing damage if not addressed. The inverter will not restart unless it is manually reset after the relay contacts return to normal.

The cooling fan is either at a standstill despite being required to operate, or its speed has significantly decelerated, indicating a malfunction. The cooling fan is essential for dissipating heat from the inverter. Without adequate cooling, the inverter will overheat and trip, potentially leading to irreversible component damage.

The resistor of the inverter's inrush current limit circuit has overheated. This typically occurs due to frequent power cycling (ON/OFF) of the inverter, which causes the inrush current limiting components to work excessively, leading to thermal stress and potential failure. Overheating can degrade or destroy these components, preventing proper inverter startup.

The reset signal (RES signal) is ON, causing the inverter to immediately shut off its output. This indicates that a reset command has been issued, either manually through a control signal or automatically by the system, placing the inverter in a non-operational state.

The cumulative energization time of the inverter has exceeded the set value in the maintenance output timer (Pr. 503). This is a reminder or pre-alarm indicating that periodic maintenance is due, based on accumulated operational hours. It is not a fault but a preventative warning, suggesting that routine checks are required.

Parameter setting was attempted in External or NET operation mode when Pr. 77 (Parameter write selection) was not '2', or parameter writing was attempted when the command source was not the operation panel. This prevents modification of parameters under specific operating conditions to maintain system integrity and prevent unintended changes.

An attempt was made to operate the inverter while the operation panel was in a locked state, preventing parameter changes or control actions. This is often a security or accidental lockout feature designed to prevent unauthorized modifications. The inverter will not respond to panel inputs until unlocked.

The output current has exceeded the detection level set in a parameter. This functions as a protective measure to prevent overcurrent conditions that could damage the motor or the inverter's power components. Incorrect parameter settings can trigger this unnecessarily, or it could indicate an actual motor overload or short circuit condition.

The component responsible for storing parameters (typically on the control circuit board) has become abnormal, indicating a potential hardware or firmware issue. This fault can lead to incorrect operation, loss of configured settings, or general system instability. Unresolved, it risks unpredictable behavior or complete system failure.

An attempt was made to read or write a parameter that is restricted by a password, preventing access or modification. This security feature protects critical parameters from unauthorized changes, ensuring system integrity and safety. Access is denied until the correct password is provided.

The resistance of the PTC thermistor, connected between terminals 2 and 10, has exceeded the set protection level (Pr. 561). This signifies that the monitored motor or component is overheating. Continuing operation under this condition poses a high risk of severe motor damage.

A communication error has occurred between the PU (Parameter Unit) and the inverter, or the communication interval has exceeded the permissible time during RS-485 communication. This also triggers if the number of communication errors exceeds the retry limit. Loss of communication means the inverter cannot receive commands or send status, interrupting operation.

The [STOP] key on the operation panel of the Parameter Unit (PU) was pressed during External operation. This indicates a manual stop command was initiated from the PU while the inverter was configured for external control, causing the inverter to cease operation.

The regenerative brake duty cycle has reached 85% or higher of the Pr. 70 (Special regenerative brake duty) setting. This is a warning that the inverter's regenerative braking capacity is nearing its thermal limit. Continuous operation at this level can lead to an overvoltage fault, damage to internal components, or overheating of the braking resistor if one is installed.

The inverter has failed to restart within the set number of retries after a preceding error or trip. This indicates a persistent underlying problem that the inverter's automatic recovery attempts could not resolve, requiring manual intervention to prevent further issues.

This alarm indicates that both safety input signals (S1 and S2) are in an open state, which triggers the safety stop function and causes the inverter output to shut off. This typically occurs as an intended safety action or due to a wiring issue, not an internal safety circuit fault.

This fault occurs when the safety circuit input terminals (across S1 and PC, or across S2 and PC) are detected as open. This indicates a break in the safety loop, signaling a potentially unsafe condition and leading to inverter shutdown. It could be due to incorrect wiring, a fault in an external safety device, or an activated safety interlock.

The safety stop function has been activated, resulting in an immediate shutdown of the inverter outputs. This critical safety measure is typically triggered by an external safety device or a wiring issue across terminals S1 and SC, or S2 and SC, indicating an open circuit in the safety chain. If misconfigured or experiencing an internal failure, it can prevent normal operation or compromise machinery safety.

The overcurrent stall prevention function has been activated. This warning indicates that the motor is encountering excessive current, possibly due to overload, insufficient acceleration time, improper torque boost settings, or mechanical binding. While a warning, prolonged activation can lead to motor or inverter damage.

The overvoltage stall prevention function has been activated, often during regeneration avoidance operation. This warning indicates that the DC bus voltage is exceeding safe limits, typically due to rapid deceleration or regenerative loads feeding energy back into the inverter. Sustained overvoltage can damage the inverter's internal components.

The voltage at the main circuit power supply has dropped below an acceptable operating level. This can be caused by issues in the power supply line, such as voltage sags, power supply capacity problems, or faulty connections. Sustained undervoltage can lead to unreliable inverter operation, internal component stress, or even damage.

This error occurs when parameter writing is set to be disabled (via Pr. 77 Parameter write selection), when frequency jump ranges (Pr. 31 to Pr. 36) overlap, or when normal communication between the PU and inverter cannot be established. It prevents new parameter settings from being applied, potentially leading to incorrect operation if desired changes are not accepted.

Parameter writing has been attempted while the inverter is actively operating (STF/STR signal is ON) and Pr. 77 Parameter write selection is not set to '2'. This error prevents parameter changes from being applied while the motor is running, which could cause instability, unsafe conditions, or unexpected behavior if allowed.