Common Error Codes for Mitsubishi Heavy Industries Central ACs and How to Deal with E43 Code

Mitsubishi Heavy Industries KXZmini series household central air-conditioning multi-split units
Figure 1: Mitsubishi Heavy Industries household central air-conditioning units.


Mitsubishi Heavy Industries Central Air Conditioner Fault Codes are a diagnostic tool that can help you determine what is wrong with your air conditioner. When your air conditioner malfunctions, a code will appear on the control panel. Here are some common Mitsubishi Heavy Industries central air conditioner fault codes.

1. Mitsubishi Heavy Industries Central AC Error Codes (A Complete List)

E01 Remote controller communication failure (wired remote controller wiring failure)
E02 Duplicate indoor unit address
E03 Indoor and outdoor unit communication not established
E04 Indoor unit address code setting error
E05 Communication failure during operation (signal transmission failure)
E06 Indoor heat exchanger temperature sensor failure
E07 Indoor return air temperature sensor failure
E08 Too high heat exchange temperature of the internal unit during heating
E09 Drainage abnormality (the indoor unit float switch operates)
E10 Single remote controller controls more than 16 indoor units.
E11 The address settings of multiple remote controls are incorrect.
E12 Address code setting error
E13 Fan motor failure
E16 Indoor fan motor failure (DC motor)
E18 Remote controller address code setting error
E19 Indoor unit operation inspection, and drainage motor inspection
E20 Abnormal indoor unit fan motor speed (DC motor)
E21 FDT unit filter switch is not closed.
E22 The internal unit cannot be recognized (the external unit mainboard program does not match).
E28 Remote controller temperature sensor abnormality
E30 Indoor unit and outdoor unit connection does not match.
E31 Duplicate outdoor unit address number
E32 Turning on the power supply L3 phase on the primary side
E35 High pressure abnormality in the refrigeration pipe
E36-1 No. 1 compressor exhaust pipe temperature failure
E36-2 No. 2 compressor exhaust pipe temperature failure
E36-3 Compressor suction pipe temperature is too low (liquid overflow is abnormal).
E37 The outdoor unit heat exchanger and subcooling coil temperature sensors are abnormal.
E38 Ambient air temperature sensor failure
E39 Exhaust pipe sensor failure
E40 High voltage fault
E41 Power transistor overheating
E42 Current cut off
E43 Internal unit overloaded or unconnected
E44-1, -2 Liquid overflow abnormality
E45 Communication failure between frequency conversion board and room control
F46 Mixed address settings exist on the same network.
E47 PAC unit overcurrent
F48-1 Abnormality in outdoor unit fan motor 1
F48-2 Abnormality in outdoor unit fan motor 2
E49 Low voltage protection
E51 Transistor overheating or inverter failure
E53 Tho-S abnormality
E55 Tho-C1 abnormality
E54-1 Low pressure sensor is disconnected or has abnormal output.
E54-2 High voltage sensor is disconnected or has abnormal output.
E56 Tho-P1, Tho-P2 abnormality
E57 Insufficient refrigerant
E58 Compressor abnormality caused by out-of-step
E59 Compressor failed to start
E60 Compressor rotor abnormality detected
E61 Master-slave communication failure
E63 Emergency stop
E75 Centralized controller abnormality
E79 The centrally controlled internal unit is not connected.
E85 Control board setting error

1.1 Wired Remote Controller (Thermostat) Model Fault Codes

Mitsubishi Heavy Industries central air conditioning control panel
Figure 2: Mitsubishi Heavy Industries central air conditioning control panel.

2. How to Clear the E43 Fault Code of Mitsubishi Heavy Industries Central Air Conditioner

Mitsubishi Heavy Industries central air conditioner fault code E43 (43E) means the internal unit is overloaded or unconnected.

The following will introduce 9 reasons that may cause this fault code, and provide corresponding solutions to help you solve this problem.

2.1 Internal Unit Overloaded

When the load that the air conditioner indoor unit carries exceeds its rated capacity, the fault code E43 will be triggered.
Solution: Check the difference between the rated capacity of the indoor unit and the current load. If the current load exceeds the rated capacity, it is necessary to reduce it or add additional indoor units to balance it.

2.2 Internal Unit Unconnected

When the internal unit of the air conditioner is unconnected or accidentally loses power, it will also cause the fault code E43.
Solution: Check whether the power connection of the indoor unit is normal and ensure that the communication between the indoor unit and the controller is smooth. If the internal unit is unconnected, it needs to be reconnected or the power cord needs repairing.

2.3 Internal Unit Failure

Failure of the internal unit itself may also lead to the fault code E43.
Solution: Check the internal unit for signs of unusual noises, odors, or cosmetic damage. If it is an internal unit failure, you need to contact the after-sales service center for repair or replacement in time.



Commercial central air conditioning indoor unit
Figure 3: Central air conditioning indoor unit.

2.4 Air Filter Clogged

When the air filter has not been cleaned or replaced for a long time, it will cause the low air flow, and thereby the increasing load on the internal unit, resulting in fault code E43.
Solution: Clean or replace the filter regularly to ensure smooth air flow.

2.5 Continuous Operation

If the indoor unit runs continuously for a long time and the temperature is too high, the fault code E43 may occur.
Solution: Appropriately adjust the use time and operating mode of the air conditioner to avoid the indoor unit overheating.

2.6 High Temperature Environment

High temperature environment is also one of the potential causes of the E43 fault code. When the outdoor temperature is too high, the cooling effect of the central air conditioning system will be affected, causing failure.

Solution:
(1) Provide additional ventilation facilities, such as fans or air conditioning coolers.
(2) Avoid using the air conditioner during high temperature periods for a long time, or reduce the power of the air conditioner during use.



Mitsubishi Heavy Industries 14 HP central air conditioner repair
Figure 4: Mitsubishi Heavy Industries central air conditioner repair.

2.7 Abnormal Voltage

Abnormal voltage may also cause the E43 fault code. When the power supply voltage is unstable or too high, the central air conditioning system will activate automatic protection and display a fault code.

Solution:
(1) Check whether the power supply is stable and eliminate the possibility of abnormal voltage.
(2) If possible, install a voltage regulator or adjust the voltage output.

2.8 Faulty Sensor

Sensor failure or damage may also trigger the E43 fault code. This means that some sensors fail to sense the ambient temperature or other parameters correctly, causing system protection to kick in.

Solution:
(1) Replace the faulty sensor to restore normal operation.
(2) Contact professional technicians for troubleshooting and repair.

2.9 Controller Failure

Finally, failure of the controller itself may also cause the fault code E43.
Solution: Check whether there is any abnormal information on the controller display. If the controller fails, you need to contact the after-sales service center for repair or replacement.



Mitsubishi Heavy Industries central air conditioning motherboard pja505a125
Figure 5: Mitsubishi Heavy Industries central air conditioning motherboard.


The solutions for Mitsubishi Heavy Industries central air conditioner fault code E43 include reducing the load, checking the connection of the indoor unit, cleaning the filter, etc. We hope that the above solutions will provide effective guidance and help for users to solve this fault code. If the problem is not resolved, please contact professional technicians or Mitsubishi Heavy Industries' after-sales service center for further support and consultation.

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