Disclaimers

  1. This page provides a simple explanation concerning content relating to error codes and their possible causes. Please note that the content may slightly differ depending on models.
  2. 212 HVAC assumes no responsibility for any accidents or troubles caused in the disassembly or repair of equipment performed according to information on this page.

Caution

If molded case circuit breakers or earth leakage circuit breakers have tripped, do not reset the breaker immediately without first checking forany problems with insulation of equipment.

Resetting breakers without a check of insulation may cause damage to equipment.

Mitsubishi air conditioning error codes

CODE: P1

RESULT: Intake sensor error.

CODE: P2 – P9

RESULT: Pipe (Liquid or 2-phase pipe) sensor error.

CODE: E6 – E7

RESULT: Indoor/outdoor unit communication error.

CODE: P4

RESULT: Drain sensor error.

CODE: P5

RESULT: Drain pump error.

CODE: PA

RESULT: Forced compressor error.

CODE: P6

RESULT: Freezing/Overheating safeguard operation.

CODE: EE

RESULT: Communication error between indoor and outdoor units.

CODE: P8

RESULT : Pipe temperature error.

CODE: E4

RESULT: Remote controller signal receiving error.

CODE: Fb

RESULT : Indoor unit control system error (memory error, etc.)

CODE: E0 – E3

RESULT: Remote controller transmission error.

CODE:  E1 – E2

RESULT: Remote controller control board error.

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

CODE: E9

RESULT: Indoor/outdoor unit communication error (Transmitting error) (Outdoor unit).

CODE: UP

RESULT: Compressor overcurrent interruption.

CODE:  U3 – U4

RESULT: Open/short of outdoor unit thermistors.

CODE: UF

RESULT: Compressor overcurrent interruption (When compressor locked).

CODE: PA

RESULT: Forced compressor error.

CODE: U2

RESULT: Abnormal high discharging temperature/49C worked/insufficient refrigerant.

CODE: U1- Ud

RESULT : Abnormal high pressure (63H worked)/Overheating safeguard operation.

CODE: U5

RESULT: Abnormal temperature of heat sink.

CODE: U8

RESULT: Outdoor unit fan safeguard stop.

CODE: U6

RESULT: Compressor overcurrent interruption/Abnormal of power module.

CODE: U7

RESULT: Abnormality of super heat due to low discharge temperature.

CODE: U9 – UH

RESULT: Abnormality such as over-voltage 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

RESULT: Error detail Mis-wiring of indoor/outdoor unit. exceed the number of indoor unit connection. Inspected unit Outdoor..

CODE: Eb

RESULT: Error detail Mis-wiring of indoor/outdoor unit. (mis-wiring disconnection) Inspected unit Outdoor.

CODE: EC

RESULT: Error detail Start-up time over. Inspected unit Outdoor.

CODE: E6

RESULT: Error detail Indoor/outdoor unit transmission error (signal receiving error). Inspected unit Indoor..

CODE: E7

RESULT: Error detail Indoor/outdoor unit transmission error (transmitting error). Inspected unit Indoor.

CODE: E8

RESULT: Error detail Indoor/outdoor unit transmission error (signal receiving error). Inspected unit Outdoor.

CODE: E9

RESULT: Error detail Indoor/outdoor unit transmission error (transmitting error). Inspected unit Outdoor.

CODE: E0

RESULT: Error detail Remote control transmission error (signal receiving error). Inspected unit Remote control

CODE: E3

RESULT: Error detail Remote control transmission error (transmitting error). Inspected unit Remote control.

CODE: E4

RESULT: Error detail Remote control transmission error (signal receiving error). Inspected unit Indoor.

CODE: E5

RESULT: Error detail Remote control transmission error (transmitting error). Inspected unit Indoor.

CODE: EF

RESULT: Error detail M-NET transmission error. Inspected unit Indoor and outdoor.

CODE: Ed

RESULT: Error detail Serial transmission error. Inspected unit Outdoor.

CODE: P1

RESULT: Error detail Abnormality of room temperature thermistor (TH1). Inspected unit Indoor.

CODE: P2

RESULT: Error detail Abnormality of pipe temperature thermistor/liquid (TH2). Inspected unit Indoor.

CODE: P4

RESULT: Error detail Abnomarlity of drain sensor (DS). Inspected unit Indoor.

CODE: P5

RESULT: Error detail Malfunction of drain-up machine. Inspected unit Indoor.

CODE: P6

RESULT: Error detail Freezing/overheating protection detect. Inspected unit Indoor.

CODE: P8

RESULT: Error detail Abnormality of pipe temperature. Inspected unit Indoor.

CODE: P9

RESULT: Error detail A-normality of pipe temperature thermistor/condenser/evaporator (TH5). Inspected unit Indoor.

CODE: F1

RESULT: Error detail Reverse phase detection.

CODE: F2

RESULT: Error detail L3 open phase detection.

CODE: F3

RESULT: Error detail 63L connector open.

CODE: F4

RESULT: Error detail 49C connector open.

CODE: F9

RESULT: Error detail Connector 2 or more open.

CODE: FA

RESULT: Error detail L2-phased open phase or 51CM connector open.

CODE: F7

RESULT : Error detail Reverse phase detection circuit (p.c.board) fault.

CODE: F8

RESULT: Error detail Input circuit fault.

CODE: U2

RESULT: Error detail Abnormal high discharging temperature.

CODE: U2

RESULT: Error detail Inner thermostat (49C) operation.

CODE: U1

RESULT: Error detail Abnormal high pressure (high pressure switch 63H worked)

CODE: U1

RESULT: Error detail Direct cut operation.

CODE: UE

RESULT: Error detail High pressure error (ball valve closed)

CODE: UL

RESULT : Error detail Over heat protection.

CODE: Ud

RESULT: Error detail Over heat protection

CODE: U6

RESULT: Error detail Compressor over current (overload) cut off.

CODE: UA

RESULT: Error detail Compressor over current (terminal relay operation).

CODE: UF

RESULT: Error detail Compressor over current (start-up locked) cut off.

CODE: UF

RESULT: Error detail Compressor over current (operating locked) cut off.

CODE: UH

RESULT: Error detail Current sensor error.

CODE: U3

RESULT: Error detail Discharge thermistor short/open.

CODE: U4

RESULT: Error detail Outdoor thermistor short/open.

Mr.Slim K-control Display of remote controller.

CODE: LED E0

RESULT: Diagnosis of malfunction Transmitting/receiving signal error. Inspected unit Indoor.

CODE: LED P1

RESULT: Diagnosis of malfunction Intake air sensor abnormal. Inspected unit Indoor.

CODE: LED P2

RESULT: Diagnosis of malfunction Pipe sensor abnormal. Inspected unit Indoor.

CODE: LED P4

RESULT: Diagnosis of malfunction Drain sensor abnormal. Inspected unit Indoor.

CODE: LED P5

RESULT: Diagnosis of malfunction Malfunctioning of the drain overflow protecting mechanism. Inspected unit Indoor.

CODE: LED P6

RESULT: Diagnosis of malfunction Abnormality of the coil frost/overheating protection mode. Inspected unit Indoor.

CODE: LED E0

RESULT: Diagnosis of malfunction Transmitting/receiving signal error. Inspected unit Indoor.

CODE: LED P3

RESULT: Diagnosis of malfunction System error (transmitting/receiving signal). Inspected unit Indoor.

CODE: LED P7

RESULT: Diagnosis of malfunction System error (address). Inspected unit Indoor.

CODE: LED E8

RESULT: Diagnosis of malfunction Outdoor unit malfunction. Inspected unit Outdoor.

Mr.Slim K-control Outdoor unit

LED ON = Operation status
LED Flash = Check code display

CODE: LED LD1

RESULT: LED ON Compressor directive, LED Flash Reverse phase detect  

CODE: LED LD2

RESULT: LED ON Heating directive , LED Flash Open phase detect  

CODE: LED LD3

RESULT: LED ON During 63H1 operation , LED Flash Pipe sensor short/open  

CODE: LED LD4

RESULT: LED ON Compressor ON , LED Flash High pressure switch (63H2) operation.  

CODE: LED LD5

RESULT: LED ON Outdoor fan ON , LED Flash Over current relay (51CM) operation.

CODE: LED LD6

RESULT: LED ON 4-way valve ON , LED Flash Thermal switch (26C) operation.

CODE: LED LD7

RESULT: LED ON Bypass valve ON , LED Flash Thermistor (TH3) overheat protection.

CODE: LED LD8

RESULT: LED ON Crankcase heater ON , LED Flash Detective 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.

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