Mitsubishi Air Conditioning error codes

Trouble shooting for Mitsubishi Air Conditioning error codes based on the results of self-diagnostics.

The modern air conditioners from Mitsubishi have a very developed self-diagnostics system, and when the control system detects an error, it blocks the operation of the entire device and displays a cause of faulty condition.

The control system of the Mitsubishi air conditioners reports that an error occurred by blinking of a light-emitting diode on the surface of the internal (or external) unit. When a particular error of an air conditioner is detected, light-emitting diodes blink in a certain order, which corresponds with a particular error. If the control system of an air conditioner detects more than one error, the error with the highest priority is displayed first and then all the following errors are displayed

After completing installation and the wiring and piping of the indoor and outdoor units, check for refrigerant leakage, looseness in the power supply or control wiring, wrong polarity, and no disconnection of one phase in the supply.

The following is a list of Mitsubishi Air Conditioning error codes.

  • P1  Intake sensor error
  • P2 P9 Pipe (Liquid or 2-phase pipe) sensor error
  • E6 E7 Indoor/outdoor unit communication error
  • P4 Drain sensor error
  • P5  Drain pump error
  • PA Forced compressor error
  • P6  Freezing/Overheating safeguard operation
  • EE  Communication error between indoor and outdoor units
  • P8  Pipe temperature error
  • E4  Remote controller signal receiving error
  • Fb  Indoor unit control system error (memory error, etc.)
  • E0 E3 Remote controller transmission error
  • E1 E2 Remote controller control board error

For details, check the LED display of the outdoor controller board.

  • E9  Indoor/outdoor unit communication error (Transmitting error) (Outdoor unit)
  • UP  Compressor overcurrent interruption
  • U3, U4  Open/short of outdoor unit thermistors
  • UF Compressor overcurrent interruption (When compressor locked)
  • U2  Abnormal high discharging temperature/49C worked/insufficient refrigerant
  • U1 Ud Abnormal high pressure (63H worked)/Overheating safeguard operation
  • U5  Abnormal temperature of heat sink
  • U8 Outdoor unit fan safeguard stop
  • U6  Compressor overcurrent interruption/Abnormal of power module
  • U7 Abnormality of super heat due to low discharge temperature
  • U9  UH Abnormality such as overvoltage or voltage shortage and abnormal synchronous signal to main circuit/ Current sensor error.

Mr.Slim A-control error code list

Display of remote controller

  • Code EA
    Error detail Mis-wiring of indoor/outdoor unit. exceed the number of indoor unit connection.
    Inspected unit Outdoor.
  • Code Eb
    Error detail Mis-wiring of indoor/outdoor unit. (mis-wiring disconnection)
    Inspected unit Outdoor.
  • Code EC
    Error detail Start-up time over
    Inspected unit Outdoor.
  • Code E6
    Error detail Indoor/outdoor unit transmission error (signal receiving error).
    Inspected unit Indoor.
  • Code E7
    Error detail Indoor/outdoor unit transmission error (transmitting error).
    Inspected unit Indoor.
  • Code E8
    Error detail Indoor/outdoor unit transmission error (signal receiving error).
    Inspected unit Outdoor.
  • Code E9
    Error detail Indoor/outdoor unit transmission error (transmitting error).
    Inspected unit Outdoor.
  • Code E0 Error detail Remote control transmission error (signal receiving error)
    Inspected unit Remote control
  • Code E3
    Error detail Remote control transmission error (transmitting error)
    Inspected unit Remote control.
  • Code E4
    Error detail Remote control transmission error (signal receiving error)
    Inspected unit Indoor.
  • Code E5
    Error detail Remote control transmission error (transmitting error)
    Inspected unit Indoor.
  • Code EF
    Error detail M-NET transmission error
    Inspected unit Indoor and outdoor.
  • Code Ed
    Error detail Serial transmission error
    Inspected unit Outdoor.
  • Code P1
    Error detail Abnolmality of room temperature thermistor (TH1).
    Inspected unit Indoor.
  • Code P2
    Error detail Abnormality of pipe temperature themistor/liquid (TH2).
    Inspected unit Indoor.
  • Code P4
    Error detail Abnomarlity of drain sensor (DS)
    Inspected unit Indoor.
  • Code P5
    Error detail Malfunction of drain-up machine.
    Inspected unit Indoor.
  • Code P6
    Error detail Freezing/overheating protection detect.
    Inspected unit Indoor.
  • Code P8
    Error detail Abnormality of pipe temperature.
    Inspected unit Indoor.
  • Code P9
    Error detail Anormality of pipe temperature thermistor/condenser/evaporator (TH5)
    Inspected unit Indoor.
  • Code F1
    Error detail Reverse phase detection.
  • Code F2
    Error detail L3 open phase detection.
  • Code F3
    Error detail 63L connector open.
  • Code F4
    Error detail 49C connector open.
  • Code F9
    Error detail Connector 2 or more open.
  • Code FA
    Error detail L2-phased open phase or 51CM connector open.
  • Code F7
    Error detail Reverse phase detection circuit (p.c.board) fault.
  • Code F8
    Error detail Input circuit fault.
  • Code U2
    Error detail Abnormal high discharging temperature.
  • Code U2
    Error detail Inner thermostat (49C) operation.
  • Code U1
    Error detail Abnormal high pressure (high pressure swicth 63H worked)
  • Code U1
    Error detail Direct cut operation.
  • Code UE
    Error detail High pressure error (ball valve closed)
  • Code UL
    Error detail Abnormal low pressure.
  • Code Ud
    Error detail Over heat protection
  • Code U6
    Error detail Compressor over current (overload) cut off.
  • Code UA
    Error detail Compressor over current (terminal relay operation).
  • Code UF
    Error detail Compressor over current (start-up locked) cut off.
  • Code UF
    Error detail Compressor over current (operating locked) cut off.
  • Code UH
    Error detail Current sensor error.
  • Code U3
    Error detail Discharge thermistor short/open.
  • Code U4
    Error detail Outdoor thermistor short/open.
  • Mr.Slim K-control
    Display of remote controller
  • LED E0
    Diagnosis of malfunction Transmitting/receiving signal error.
    Inspected unit Indoor.
  • LED P1
    Diagnosis of malfunction Intake air sensor abnormal.
    Inspected unit Indoor.
  • LED P2
    Diagnosis of malfunction Pipe sensor abnormal.
    Inspected unit Indoor.
  • LED P4
    Diagnosis of malfunction Drain sensor abnormal.
    Inspected unit Indoor.
  • LED P5
    Diagnosis of malfunction Malfunctioning of the drain overflow protecting mechanism.
    Inspected unit Indoor.
  • LED P6
    Diagnosis of malfunction Abnomality of the coil frost/overheating protection mode.
    Inspected unit Indoor.
  • LED P3
    Diagnosis of malfunction System error (transmitting/receiving signal).
    Inspected unit Indoor.
  • LED P7
    Diagnosis of malfunction System error (address)
    Inspected unit Indoor.
  • LED P8
    Diagnosis of malfunction Outdoor unit malfunction
    Inspected unit Outdoor.
  • Mr.Slim K-control PUH-EK
    Outdoor unit
  • LED ON = Operation status
    LED Flash = Check code diplay
  • LED LD1
    LED ON Compressor directive
    LED Flash Reverse phase detect
  • LED LD2
    LED ON Heating directive
    LED Flash Open phase detect
  • LED LD3
    LED ON During 63H1 operation
    LED Flash Pipe sensor short/open
  • LED LD4
    LED ON Compressor ON
    LED Flash High pressure swicth (63H2) operation.
  • LED LD5
    LED ON Outdoor fan ON
    LED Flash Over current relay (51CM) operation.
  • LED LD6
    LED ON 4-way valve ON
    LED Flash Thermal swicth (26C) operation.
  • LED LD7
    LED ON Bypass valve ON
    LED Flash Thermistor (TH3) overheat protection.
  • LED LD8
    LED ON Crankcase heater ON
    LED Flash Devective input.

 

Mitsubishi Mr. Slim Error Codes – Membrane type remote controllers

Check code Diagnosis of malfunction Cause Check points
EO Signal transmitting/receiving error

(Indoor controller does not respond to remote controller signal)

During individual unit control

1) Bad contact of transmission wire

2) Signal transmitting/receiving circuit is abnormal.

1) Check the transmission wire.

2) Check with another remote controller. If “EO” is still indicated, replace the indoor controller board.

If other check code appears. replace the original remote controller.

P1 Abnormality of room temperature thermistor (RT1) 1) Bad contact of thermistor

2) Damaged thermistor

1) Check the thermistor.

2) Measure the resistance of the thermistor.

Normal resistance should be as follows.

32°F····15kΩ 86°F·····4.3kΩ

50°F······9.6kΩ 104°F·····3.0kΩ

68°F······6.3kΩ

If the resistance is normal, replace the indoor controller board.

P2 Abnormality of indoor coil thermistor (RT2) 1) Bad contact of thermistor

2) Damaged thermistor

1) Check the thermistor.

2) Measure the resistance of the thermistor.

Normal resistance should be as follows.

32°F····15kΩ 86°F·····4.3kΩ

50°F······9.6kΩ 104°F·····3.0kΩ

68°F······6.3kΩ

If the resistance is normal, replace the indoor controller board.

P3 Signal transmission error

(Remote controller does not respond to indoor controller signal)

1) Bad contact of transmission wire

2) Signal transmitting/receiving circuit is abnormal.

3) Wrong operation due to noise

wave emitted by other appliances

1) Check the transmission wire.

2) Check with another remote controller.

If “P3” is still indicated, replace the indoor board.

If other check code appears, replace the original remote controller.

3) Short-circuit between 1 and ➁ of CN40 and attach CN40 to the following units.

● Second unit in twin control

● Second and third units in triple control

● Sub units in group control

P4 Abnormality of drain sensor 1) Bad contact of transmission wire

2) Damaged thermistor

1) Check the connector.

2) Measure the resistance of the thermistor ➃ – ➄.

As for the normal resistance, refer to the case of P1.

If the resistance is normal, replace the indoor controller board.

P5 Malfunction of drain pump 1) Malfunction of drain pump

2) Damaged drain sensor

1) Check the drain pump.

2) ● Check the drain sensor.

● Check the drain sensor heater. Normal resistance should be 82Ω.

If the resistance is normal, replace the indoor controller board.

P6 Coil frost protection is working. 1) Short cycle of air cycle

2) Dirty air filter

3) Damaged fan

4) Abnormal refrigerant

1) Clear obstructions from the air cycle.

2) Clean the air filter

3) Check the fan.

4) Check the refrigerant temperature.

P7 System error 1) Wrong address-setting

2) Signal transmitting/receiving circuit of remote controller is abnormal.

3) Wrong SW6-setting

1) Check the address-setting.

2) Check with another remote controller. If check code other than “P7” appears, replace the original remote controller.

3) Check SW6 setting.

P8 Abnormality in outdoor unit 1) Wrong wiring of indoor/outdoor connecting wire

2) Reversed phase

3) Protection device is working

4) Damaged outdoor coil thermistor

1) Check the indoor/outdoor connecting wire.

2) Change the connection of electric wiring.

3) Check the protection device.

4) Measure the resistance of the outdoor coil thermistor. If the resistance is normal, replace the outdoor controller board.

 

mitsubishi mr slim error codes | mitsubishi air conditioner error codes