Mitsubishi Electric PUZ-HA30

The power circuit board has detected an overvoltage condition in the input power supply. This condition indicates that the incoming voltage exceeds safe operating limits, posing a risk of damage to sensitive electronic components if not corrected.

The power circuit board has detected an undervoltage condition in the input power supply. This can lead to improper operation, instability, or failure of the system's components, particularly the compressor, due to insufficient power.

An open circuit is detected in either the L1 or L2 phase of the main power input, indicating a missing power phase. This typically prevents the power circuit board from receiving a complete supply, leading to system shutdown or malfunction.

An abnormality is detected in the power synchronous signal, which is crucial for the controller circuit board to synchronize with the incoming power frequency. A faulty signal can lead to unstable operation of power components and incorrect timing control.

An error related to the Automatic Current Tracking Module (ACTM) has occurred. This module is essential for accurate current sensing and control, and an error can impact compressor operation and protection, often associated with the power board.

This fault, 'M-NET NO RESPONSE', occurs when the system transmits a message and receives an acknowledgement, but fails to receive the expected response command. This condition repeats 6 times over 60 seconds before triggering the error. Primary causes include electrical noise on the M-NET transmission wire, exceeding the maximum permissible wire length, or using an incompatible cable type. Persistent communication failure will disrupt central control, monitoring, and overall system functionality.

This abnormality is detected if a message was transmitted, an acknowledgment (ACK) of receipt was received, but no response command returns. The transmitting side detects this abnormality every 10 seconds, 6 times continuously. The remote controller displays the address and attribute of the controller that did not reply (ACK).

A main or sub remote controller cannot receive transmissions from an indoor unit (refrigerant address '0') for 3 minutes, or a sub-remote controller cannot receive any signal for 3 minutes. Potential causes include contact failure or miswiring of the remote controller transmission wire, all remote controllers being set as 'sub', exceeding total wiring length (max 200m) or number of connected indoor units (max 16) or remote controllers (max 2), a defective transmitting/receiving circuit, or noise in the transmission wire.

A communication error has occurred with an indoor unit or other connected device, rather than the outdoor unit itself. The specific indoor unit (0-7) experiencing the error is typically indicated by the last digit. This error prevents proper system control and coordination.

Data cannot be read normally from the nonvolatile memory of the remote controller control board. This indicates a defective remote controller.

The clock function of the remote controller cannot be operated normally. This indicates a defective remote controller.

The remote controller cannot find a blank transmission path for 6 seconds and cannot transmit, or the indoor controller board cannot find a blank transmission path. This can be due to multiple remote controllers set as 'main', a remote controller connected to multiple indoor units, repeated refrigerant addresses, a defective transmitting/receiving circuit on the remote controller or indoor controller board, or noise in the remote controller transmission wire.

The indoor controller board cannot receive any data normally from the remote controller board or from other indoor controller boards for 3 minutes, or cannot receive any signal from the remote controller for 3 minutes. Potential causes include contact failure or miswiring of the remote controller transmission wire, all remote controllers being set as 'sub', exceeding total wiring length (max 200m) or number of connected indoor units (max 16) or remote controllers (max 2), a defective transmitting/receiving circuit, or noise in the transmission wire.

The remote controller receives transmitted data at the same time, compares it, and detects different data 10 continuous times, or the indoor controller board performs the same comparison and detects different data 10 continuous times. This can be due to multiple remote controllers set as 'main', a remote controller connected to multiple indoor units, repeated refrigerant addresses, a defective transmitting/receiving circuit on the remote controller or indoor controller board, or noise in the remote controller transmission wire.

The indoor controller board fails to receive signals normally for 6 minutes after power-on, or 10 minutes during operation, or from the outdoor board in twin systems. This points to communication wire contact failure, short circuits, miswiring, noise, or defects in communication circuits or fan motor/rush current resistor. It severely impairs the indoor unit's ability to coordinate with the outdoor unit.

The indoor controller board fails to receive any signal normally for 6 minutes after power-on, or for 10 minutes, or if 2 or more indoor units are connected to an outdoor unit and the indoor controller board doesn't receive a signal for 10 minutes allowing outdoor transmission. Potential causes include contact failure, short circuit, or miswiring of the indoor/outdoor unit connecting wire, defective transmitting/receiving circuits (outdoor controller, indoor controller), noise, a defective fan motor, or a defective rush current resistor. Another indoor controller board in a twin system may also be faulty.

The outdoor unit is experiencing an error in receiving communication signals from the indoor unit. This indicates a breakdown in the communication link, preventing the outdoor unit from receiving necessary commands or data, which can lead to improper operation or system shutdown.

The outdoor controller circuit board fails to receive any signal normally for 10 minutes. This can be caused by contact failure in the indoor/outdoor unit connecting wire, defective communication circuits in either the outdoor controller board or the indoor controller board, or noise interference within the indoor/outdoor unit connecting wire.

The outdoor unit is experiencing an error in transmitting communication signals to the indoor unit. This indicates a breakdown in the communication link, preventing the indoor unit from receiving necessary status or data from the outdoor unit, which can lead to improper operation or system shutdown.

The outdoor controller circuit board detects '0' receiving 10 times continuously despite transmitting '1', or it fails to find a blank transmission path for 10 minutes. This indicates potential contact failure or looseness in the indoor/outdoor unit connecting wire, a defective communication circuit on the outdoor controller circuit board, or noise interference in the power supply or connecting wire.

The connecting wiring between indoor and outdoor units is either miswired, or the system configuration includes an excessive number of indoor units (four or more). This condition disrupts proper communication and system control, preventing normal operation.

The connecting wiring between the indoor and outdoor units has been miswired (converse wiring) or a disconnection has occurred. This critical fault prevents proper communication and control between the units, leading to system malfunction.

This error indicates a failure in serial communication, affecting either the link between the outdoor controller circuit board and the outdoor power circuit board, or the M-NET board. Common causes include wire breaks, loose connector contacts, or defective communication circuits on the involved boards. Without proper communication, the system cannot be controlled or monitored effectively, leading to operational failure or incorrect responses.

This error indicates a failure in serial communication. It can occur between the outdoor controller circuit board and the outdoor power circuit board, or between the outdoor controller circuit board and the M-NET board. Causes include broken wires, contact failures in connectors (CN, CNMNT, CND), defective communication circuits on the boards, or noise interference on the M-NET transmission wire.

This code appears when an unrecognized or non-defined error code is received by the system. It often points to communication anomalies, severe noise interference, an incompatible outdoor unit (not an inverter model), or an incorrect remote controller model. This issue prevents the system from accurately diagnosing problems and may indicate fundamental compatibility or communication failures.

This code is displayed when the unit receives an undefined error code. Possible root causes include noise in the remote controller transmission wire or indoor/outdoor connecting wire, the outdoor unit not being an inverter model, or the use of an incompatible remote controller model (PAR-S21A).

The P8 abnormality is detected when there is an insufficient temperature difference between the indoor room temperature (TH1) and the indoor pipe temperature (TH or TH) during cooling or heating operation. In cooling mode, the pipe temperature must be within the cooling range (TH_pipe - TH1 < -3°C) after 9 minutes. In heating mode, the condenser/evaporator pipe temperature (TH) must be within the heating range (TH_pipe - TH1 > 3°C) after 17 minutes. Potential root causes include refrigerant shortage, disconnected thermistor holder, defective refrigerant circuit, converse connection of extension pipes, or incomplete opening of stop valves.

An open or short circuit is detected in one or more outdoor unit thermistors (TH3, TH32, TH33, TH6, TH7, and TH8). These sensors are critical for monitoring various temperatures within the outdoor unit's refrigerant circuit and ambient conditions, affecting system control. Open detection for TH3, TH32, TH33, TH6 is inoperative for 10 seconds to 10 minutes after compressor start and 10 minutes after/during defrosting.

The discharge temperature thermistor (TH4) circuit is detected as either open (temperature reading 37°F [3°C] or less) or short (temperature reading 422°F [217°C] or more) during compressor operation. This fault prevents accurate monitoring of compressor discharge temperature, impacting system protection and control. Detection is inoperative for the first 10 minutes of compressor start-up and during/after defrosting.

The heatsink thermistor (TH8) detects an abnormal temperature, either too low (below -40°F [-40°C]) or too high (above 183°F [84°C]). This indicates a potential issue with the outdoor fan, restricted airflow, excessive ambient temperature (above 114°F [46°C]), or a fault in the thermistor or associated circuit boards.

An abnormality is detected in the power module, often signaled by overcurrent during module operation (which can trigger UF or UP errors). This critical fault can be caused by a closed outdoor stop valve, low power supply voltage, incorrect or loose compressor wiring, or a defective compressor or outdoor power circuit board.

The system continuously detects discharge superheat less than or equal to -15°C [5°F] for 3 minutes, even with the linear expansion valve (LEV) at its minimum open pulse and the compressor running for 10 minutes. This indicates potential liquid floodback to the compressor, posing a significant risk of compressor damage.

The outdoor fan motor is abnormal if its rotational frequency is detected as abnormal during operation, specifically 100 rpm or below for 1 second at 30°C or more, or 30 rpm or below/1000 rpm or more for 1 minute continuously. This indicates a problem with the fan motor or its control circuit. Failing to resolve this can lead to insufficient heat exchange, compressor overheating, and overall system performance degradation.

This code indicates either an abnormal current detection by the current sensor (-1.5A to 1.5A) during compressor operation, or an abnormal rotational frequency of the outdoor fan motor. Fan motor abnormality occurs if rotation is below 100 rpm for 1 second at >=20°C ambient temperature, or below 80 rpm / above 1300 rpm continuously for 1 minute. Potential root causes include incorrect compressor wiring, a defective current sensor circuit on the outdoor power circuit board, DC fan motor failure, or an issue with the outdoor circuit controller board.

This fault is detected when DC bus voltage decreases to 210V, momentarily drops to 200V, rises to 400V, or if input current drops to 0.4A (when frequency >= 30Hz or compressor current >= 1A) during compressor operation. It signals significant power supply instability or a fault within the main circuit components like the noise filter or ACT module. Unresolved, this can lead to severe damage to the compressor and other sensitive electronic components due to improper voltage conditions.

This fault is detected during compressor operation if the DC bus voltage decreases to 310V, momentarily drops to 300V, or increases to 700V. It can also be triggered if the outdoor unit input current drops to 0.4A when operating frequency is >=30Hz or compressor current is >=3A. Root causes may include unstable power supply, compressor wiring issues, a defective noise filter circuit board, a faulty ACT module, its drive circuit, or loose connections for CN7C, CNAF, CN50, or CN51.

This fault triggers if the outdoor pipe thermistor (TH1) detects 70°C (158°F) or more during compressor operation. It indicates excessive heat within the outdoor unit, likely due to restricted airflow, a malfunctioning outdoor fan, or a faulty thermistor. Persistent overheating can lead to compressor failure and significant reduction in cooling efficiency.

The outdoor pipe thermistor (TH2) detects a temperature of 70°C [158°F] or more during compressor operation. This indicates either a defective outdoor fan (fan motor), a short cycle of the outdoor unit during cooling operation, or a faulty outdoor pipe thermistor (TH2).

Compressor overcurrent is detected within 30 seconds of starting, indicating a locked rotor condition. This can be caused by a closed stop valve, low power supply voltage, incorrect compressor wiring, or a defective compressor or outdoor power board. This fault causes an immediate shutdown to prevent damage, but recurring issues can severely shorten compressor lifespan.

An overcurrent condition on the DC bus or compressor is detected within 30 seconds after the compressor starts operating. This indicates a locked compressor state. Common causes include a closed stop valve, decreased power supply voltage, loose, disconnected, or reversed compressor wiring connection, a defective compressor, or a faulty outdoor power board.

Abnormal if the current sensor detects -1.0 A to 1.0 A during compressor operation. This error indicates a potential issue with the current sensor circuit itself or the compressor's wiring. If left unaddressed, it can lead to improper compressor control, reduced efficiency, or even damage due to lack of accurate current feedback.

The 63L low-pressure switch activates, indicating system pressure below -0.07 MPa (-10 PSIG) during compressor operation. This critical fault suggests a closed outdoor unit stop valve, significant refrigerant leakage/shortage, or a malfunction in the linear expansion valve. Ignoring this can lead to severe and irreparable damage to the compressor.

The low-pressure switch (63L) is activated, detecting pressure under -0.01MPa [-1.5PSIG] during compressor operation. This indicates either a closed stop valve on the outdoor unit, disconnection or loose connection of the 63L connector or the 63L switch itself, a defective outdoor controller board, refrigerant leakage or shortage, or a malfunction of the linear expansion valve.

Compressor overcurrent is detected after 30 seconds of compressor operation, indicating an excessive current draw. Potential causes include a closed stop valve, insufficient power supply voltage, incorrect compressor wiring, fan malfunctions, short cycling, or a defective compressor or outdoor controller board input circuit. This fault protects the compressor from immediate damage but requires prompt resolution to prevent component failure.

An overcurrent condition on the DC bus or compressor is detected after the compressor has been operating for 30 seconds. This differs from UF (100) which occurs within 30 seconds of start-up. Causes can include a closed stop valve, decreased power supply voltage, loose/disconnected/reversed compressor wiring, defective indoor/outdoor fans, short cycling of units, a defective input circuit of the outdoor controller board, or a defective compressor.