MHI Air Conditioning

After the initial 'startup' sequence, if only the green LED (LED1) on the outdoor board lights up, it means either there is no outdoor unit with address 0, or the remote controller transmission wire is open.

The OPERATION INDICATOR lamp blinks once in 'Output pattern A' from the indoor unit, indicating a communication issue between the indoor and outdoor units, specifically a transmitting error from the outdoor unit.

The OPERATION INDICATOR lamp blinks twice in 'Output pattern A' from the indoor unit, suggesting that there is an open circuit or short circuit in the outdoor unit's thermistors.

The OPERATION INDICATOR lamp blinks three times in 'Output pattern A' from the indoor unit, indicating that the compressor has stopped due to an overcurrent, likely because it is locked.

When sending settings from the remote control to the air conditioner, you should hear three beeps from the indoor unit. If you do not hear these beeps, the settings were not received by the air conditioner.

After you stop the air conditioner, it will not restart immediately for about 3 minutes. This is a normal protective feature, where a microcomputer's timer automatically starts it up again after the delay.

The OPERATION INDICATOR lamp blinks four times in 'Output pattern A' from the indoor unit. This points to either an abnormally high discharge temperature or insufficient refrigerant in the system.

The OPERATION INDICATOR lamp blinks five times in 'Output pattern A' from the indoor unit. This signifies an abnormal high pressure situation or that the overheating protection has activated.

The OPERATION INDICATOR lamp blinks six times in 'Output pattern A' from the indoor unit, indicating an abnormal temperature of the heatsink in the outdoor unit.

The OPERATION INDICATOR lamp blinks seven times in 'Output pattern A' from the indoor unit, indicating that the outdoor unit fan has stopped due to a protection mechanism.

The OPERATION INDICATOR lamp blinks eight times in 'Output pattern A' from the indoor unit. This points to either a compressor overcurrent or an abnormality within the power module.

The OPERATION INDICATOR lamp blinks nine times in 'Output pattern A' from the indoor unit. This indicates an abnormality like overvoltage, undervoltage, an abnormal synchronous signal to the main circuit, or a current sensor error.

The OPERATION INDICATOR lamp blinks fourteen times in 'Output pattern A' from the indoor unit, indicating a general 'other error' condition in the outdoor unit.

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks one time alternately, indicating a serial communication error between the outdoor controller board and the outdoor power board.

If the remote control display shows any abnormal condition that doesn't resolve with battery replacement or normal operation, a reset may be needed.

The air conditioner is completely unresponsive and does not turn on. This can be caused by a lack of power supply or incorrect timer settings.

The digital display area shows an alarm code, indicating a general operational fault or issue within the refrigeration unit. This code is crucial for diagnosing specific problems.

If you observe the air conditioner's power cable becoming extremely hot to the touch or if its protective covering is cracked, this is a serious electrical hazard.

When you are making changes to settings within a sub-menu, the system will not save your adjustments if the MENU switch is held down for more than 1 second. Your changes will also be lost if the setting process is aborted before completion, returning the display to the normal screen without applying your selections.

If no operation is performed on the remote control for 60 seconds while in setting mode, the changes made become invalid, and the setting mode ends. The remote control display along with all program numbers (P1, P2, P3, P4) will blink for 10 seconds.

If the remote control display fades or becomes difficult to read, it indicates that the remote control batteries are exhausted and need to be replaced.

During startup or operation, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks six times alternately, indicating an indoor/outdoor unit communication error, specifically a transmitting error detected by the indoor unit.

This indicates an error with the remote controller's ability to transmit signals.

During startup or operation, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks seven times alternately, indicating a remote controller signal receiving error detected by the remote controller itself.

During startup or operation, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks five times alternately, indicating an indoor/outdoor unit communication error, specifically a signal receiving error detected by the indoor unit.

During startup or operation, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks three times alternately, indicating that an undefined error code has been detected.

During startup or operation, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks four times alternately, indicating incorrect wiring of the indoor/outdoor unit connecting wire or too many indoor units connected (4 or more).

After the initial 'startup' sequence, if the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks once alternately, it indicates incorrect wiring between the indoor and outdoor units, specifically wrong polarity for S1, S2, S3.

During startup, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks twice alternately, indicating that the unit exceeded its allowed startup time.

During startup or operation, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks nine times alternately, indicating a remote controller signal receiving error detected by the indoor unit.

The OPERATION INDICATOR lamp blinks seven times in 'Output pattern B', indicating a communication error between the indoor and outdoor units.

During startup or operation, the outdoor unit's LED1 (green) blinks twice and LED2 (red) blinks eight times alternately, indicating a remote controller transmitting error detected by the remote controller.

After the initial 'startup' sequence, if the outdoor unit's LED1 (green) blinks once and LED2 (red) blinks once alternately, it indicates an incorrect connection of the outdoor terminal block (L1, L2, S1, S2, S3).

After the initial 'startup' sequence, if the outdoor unit's LED1 (green) blinks once and LED2 (red) blinks twice alternately, it indicates that a protection device connector on the outdoor unit is open.

After the air conditioner operation has been stopped, the indoor or outdoor fan continues to run for a short period. The indoor fan may run for up to 2 hours if CLEAN operation is set, and the outdoor fan for about 1 minute to protect the unit.

The remote controller LCD displays 'Fb', indicating an abnormality with the indoor controller board.

If the air conditioner's fuse or electrical switch blows repeatedly, it indicates a persistent electrical problem that requires professional attention.

You hear a hissing or clicking sound from the unit. This sound is caused by the normal operation of the refrigerant control valves or other electric components within the air conditioner.

When the Child Lock function is set, the lock icon is displayed on the remote control. This prevents accidental operation changes, allowing only the ON/OFF button to function.

If the air conditioner operates for an extended period in conditions of high humidity, moisture may condense on the air outlet grills and start dripping.

When you transmit a signal from the remote control to the air conditioner, a receiving beep should be emitted by the indoor unit. If this beep is not heard, or if the remote control display fades, it indicates that the remote control batteries are exhausted.

When you press a button on the remote control, the air conditioner does not make a beep sound. This indicates that it did not receive the signal, often due to exhausted batteries.

After a power cut, the air conditioner does not restart automatically even when power is restored. This happens if the auto restart function is not enabled on your unit.

When setting the ON-TIMER, the timer setting will not be completed if the final button press is not made within 60 seconds of the previous step. The timer display will not change from blinking to steady.

The remote controller LCD displays 'P1', indicating an abnormality with the room temperature thermistor (TH1).

The remote controller LCD displays 'P2', indicating an abnormality with the pipe temperature thermistor (TH2) on the liquid line.

The remote controller LCD displays 'P4', indicating an abnormality with the drain sensor or that the float switch connector is open.

The remote controller LCD displays 'P5', indicating that the drain overflow protection mechanism has been activated.

The OPERATION INDICATOR lamp blinks five times in 'Output pattern B'. This indicates a drain pump error or that the compressor has been forcibly stopped due to a water leakage abnormality.

The remote controller LCD displays 'P6', indicating that either freezing protection (in cooling mode) or overheating protection (in heating mode) is currently active.

The remote controller LCD displays 'P8', indicating a general abnormality of the pipe temperature.

The remote controller LCD displays 'P9', indicating an abnormality with the pipe temperature thermistor related to the condenser or evaporator.

When setting up two air conditioners in the same room to use separate remote controls, after pressing the ACL switch on the remote control, the indoor unit should emit a 'peep' sound. If this sound is not heard, the setting was not received by the indoor unit.

The indoor unit emits a single 'Pip' buzzer sound. This sound indicates that the air conditioner has been turned off by pressing the ON/OFF button on the remote control.

The indoor unit emits a 'PipPip' buzzer sound. This sound indicates that the preset temperature has been set to 24°C, the AUTO operation mode has been selected, or automatic airflow has been chosen.

The remote controller displays 'PLEASE WAIT' for a short period after power-on (approx. 2 minutes) during normal system startup, or for about 30 seconds after canceling function selection. During this time, the remote controller cannot be operated.

The air conditioner is not providing sufficient cooling or heating to the room. This could be due to various factors affecting its performance or environment.

If you experience any abnormality with the air conditioner, and it persists even after turning off the power source, waiting 3 minutes, and restarting the operation with the remote control, it indicates a persistent fault.

The display on the remote control appears dim or fades, making it hard to read. This is a clear indicator that the batteries in the remote control are running low or are exhausted.

The remote control fails to operate the unit or shows an abnormal display. This indicates a problem with the remote itself or its communication with the air conditioner.

The air conditioner does not respond when you try to operate it with the remote control. This can be due to interference, battery issues, or obstacles.

The RUN light on your air conditioner flashes twice, indicating an error with the room temperature sensor. This sensor helps the unit control the indoor temperature accurately.

The compressor's rotor is locked, meaning it cannot spin. This is a serious mechanical or electrical fault within the compressor.

The system has detected an interruption or anomaly in the electrical current. This could be due to several electrical issues with the compressor or power supply.

The outdoor unit is experiencing a general fault. The specific cause points to a wiring issue with the compressor.

The system is drawing too much electrical current. This can be caused by the compressor struggling to operate.

An error has occurred with the power transistor, a key component in controlling the power flow to the compressor. This can be triggered by various operating conditions.

The system has detected that a service valve is closed, preventing the proper flow of refrigerant. This can happen during installation or maintenance.

During heating operation, the green RUN light on the indoor unit will blink with a pattern of 1.5 seconds ON and 0.5 seconds OFF. This indicates that the airflow is temporarily stopped to prevent cold air from blowing out.

During heating operation, the unit temporarily stops blowing air or blows non-warm air, and the RUN light blinks with this pattern. This is normal during the 'HOT KEEP' program to warm up the indoor heat exchanger or during automatic defrosting.

The RUN light blinks slowly (1.5 seconds on, 0.5 seconds off) when starting the DRY operation. This indicates the indoor fan may temporarily stop to prevent re-evaporation of dehumidified moisture and to save energy, which is normal behavior.

The RUN light remains illuminated even after the air conditioner operation has been stopped. This is normal behavior if the unit was in SELF CLEAN operation; the RUN light turns off when the CLEAN operation finishes.

During DRY (dehumidification) operation, the indoor fan may stop. This is a normal function designed to prevent previously dehumidified moisture from re-evaporating and to save energy.

The outdoor unit's fan motor is not working correctly. This fan helps dissipate heat from the outdoor coil.

There is a communication problem between the indoor and outdoor units. This prevents them from coordinating operation.

The compressor in the outdoor unit has overheated. This could be due to issues with refrigerant levels, sensors, or restricted flow.

The RUN light on your air conditioner unit is continuously flashing, indicating a problem with the outdoor temperature sensor. This could be due to a faulty sensor or an issue with its wiring.

The indoor air inlet panel is detected as open. For safety and proper operation, this panel needs to be securely closed.

The system has activated a protection mechanism due to excessively high pressure in the cooling circuit. This can indicate an overcharge of refrigerant or an issue with the outdoor unit.

The RUN light is on and flashes once, indicating an error with the power transistor. This component is crucial for controlling power to the compressor and other parts of the outdoor unit.

The RUN light is on and flashes two times, indicating an error with the discharge pipe sensor. This sensor monitors the temperature of the refrigerant discharge pipe.

The RUN light is on and flashes five times, indicating a rotor lock condition. This typically points to an issue with the compressor, which is vital for the air conditioning process.

The green RUN light on the indoor unit will blink quickly. This indicates that an invalid operation mode has been selected.

The green RUN light on the indoor unit will blink slowly in a pattern of 3.5 seconds ON and 0.5 seconds OFF. This indicates that the AUTO OFF operation is active while the unit is in standby.

The green RUN light on the indoor unit display will blink slowly in a pattern of 3 seconds ON and 1 second OFF. This indicates that the SELF CLEAN operation is currently active.

The green RUN light remains illuminated even after the main operation of the air conditioner has been stopped. This indicates that the CLEAN operation is currently active. The RUN light will turn off when the CLEAN operation finishes.

If both the green RUN light and the yellow TIMER light on the unit display section blink quickly (0.5 seconds ON, 0.5 seconds OFF) or if these lights do not work at all, it indicates a serious malfunction.

You hear a slight cracking sound from the unit. This sound is caused by heat expansion or contraction of the plastic and metal parts as the unit heats up or cools down, which is normal.

You hear a slight gurgling sound coming from the unit. This sound is caused by the refrigerating liquid moving within the air conditioning system and is considered normal.

Air blown out during operation has a slight smell. This is usually caused by tobacco or cosmetics adhering to the unit's filters or internal components, which are then recirculated with the air.

It is possible to see some steam escaping from the unit during cooling. This typically happens when the room's temperature and humidity levels are very high.

If the air conditioner emits unusual or strange noises during operation (e.g., grinding, rattling, clunking, or hissing sounds not related to normal refrigerant flow), it could indicate a mechanical or internal fault.

If any switch on the air conditioner or its remote control (other than the power switch which blows fuses) fails to activate properly, it could indicate a faulty component.

When setting the current time on the remote control, the setting is not completed if the final button press is not made within 60 seconds of the previous step. The time display will not change from blinking to steady.

The TIMER light flashes once, indicating a current cut or overcurrent situation. This means the unit detected an electrical current higher than normal, often a safety measure.

The outdoor unit's discharge pipe sensor is experiencing a fault. This sensor measures the temperature of the refrigerant as it leaves the compressor.

The TIMER light flashes twice, indicating that the compressor has overheated. This is a safety mechanism to prevent damage to the unit.

The outdoor unit has detected an issue with its heat exchanger sensor. This sensor monitors temperature in the outdoor coil.

The TIMER light flashes three times, indicating an error in signal transmission between the indoor and outdoor units. This means the units are not communicating correctly.

The outdoor unit's suction pipe sensor has an error. This sensor monitors the refrigerant temperature as it returns to the compressor.

The TIMER light on your air conditioner flashes four times, signaling an error with the heat exchanger sensor. This sensor is crucial for monitoring the temperature within the heat exchanger.

The outdoor unit's temperature sensor is faulty or disconnected. This sensor provides crucial data for the system's operation.

The TIMER light flashes five times, indicating an error with the outdoor fan motor. This fan helps dissipate heat from the outdoor unit.

The system has detected that a service valve is closed. Service valves are critical for the proper flow of refrigerant in the system.

The TIMER light flashes six times, indicating an error with the indoor fan motor. This fan is responsible for circulating conditioned air within your room.

The indoor unit has detected a general circuit malfunction. This indicates an electrical problem within the system.

The TIMER light flashes seven times, indicating that the cooling high pressure protection has been activated. This usually means there's excessively high pressure in the refrigeration system during cooling mode.

The system has detected that the refrigerant level is too low. This can lead to poor cooling or heating performance.

The yellow TIMER light on the indoor unit display illuminates. This indicates that a TIMER operation (ON TIMER, OFF TIMER, SLEEP TIMER, or WEEKLY TIMER) is currently active.

If nearby electronic equipment like TVs or radios start to malfunction or experience interference when the air conditioner is operating, it suggests the air conditioner is causing electromagnetic interference.

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks four times alternately, indicating abnormal high pressure due to the high-pressure switch (63H) activating.

The remote controller LCD displays codes in the range U1 to UP, indicating a general malfunction within the outdoor unit.

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks two times alternately, indicating an abnormality of the shell thermostat and/or discharge temperature sensor (TH4).

During startup or operation, the outdoor unit's LED1 (green) blinks four times and LED2 (red) blinks three times alternately, indicating an abnormality within the power module.

During startup or operation, the outdoor unit's LED1 (green) blinks four times and LED2 (red) blinks four times alternately, indicating an open circuit or short circuit in the discharge thermistor (TH4).

During startup or operation, the outdoor unit's LED1 (green) blinks four times and LED2 (red) blinks two times alternately, indicating an abnormality of the current sensor on the P.B. board.

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks three times alternately, indicating an abnormality of superheat due to a low discharge temperature.

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks five times alternately, indicating abnormal low pressure due to the low-pressure switch (63L) activating.

During startup or operation, the outdoor unit's LED1 (green) blinks four times and LED2 (red) blinks five times alternately, indicating an open circuit or short circuit in various outdoor thermistors (TH3, TH32, TH33, TH6, TH7, TH8).

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks six times alternately, indicating an abnormality in the rotational speed of the outdoor fan motor.

During startup or operation, the outdoor unit's LED1 (green) blinks four times and LED2 (red) blinks one time alternately, indicating that the compressor has stopped due to an overcurrent.

After a temporary loss of power, the air conditioner does not automatically resume operation even when power is restored. This indicates that the auto restart function might not be enabled.

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks seven times alternately, indicating compressor overcurrent protection activation, potentially due to a locked compressor during startup.

A whistling noise is heard from the outdoor unit. This sound indicates that the revolution speed of the compressor is either increasing or decreasing, which is a normal part of its operation.