Mitsubishi MR. Slim air conditioner error codes

Trouble shooting for Mitsubishi air conditioners 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.

Mitsubishi error codes air conditioning malfunction

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.

Mitsubishi Mr.Slim A-control air conditioning 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.

Mitsubishi Mr.Slim K-control air conditioning error codes

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.

Mitsubishi Mr.Slim air conditioning 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 AC Error Codes

Membrane type remote controllers

Check codeDiagnosis of malfunctionCauseCheck points
EOSignal 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.
P1Abnormality 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.
P2Abnormality 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.
P3Signal 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
P4Abnormality of drain sensor1) 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.
P5Malfunction of drain pump1) 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.
P6Coil 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.
P7System error1) 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.
P8Abnormality in outdoor unit1) 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 Electric Ecodan EHSC series air conditioner error codes

CodeErrorAction
L3Circulation water temperature overheat protectionFlow rate may be reduced check for;
• Water leakage
• Strainer blockage
• Water circulation pump function (Error code may display during filling of primary circuit, complete filling and reset error code.)
L4DHW tank water temperature overheat protectionCheck the immersion heater and it's contactor.
L5Indoor unit temperature thermistor (THW1, THW2, THW5, THW6, THW7, THW8, THW9) failureCheck resistance across the thermistor.
L6Circulation water freeze protectionSee Action for L3.
L8Heating operation errorRe-attach any thermistors that have become dislodged.
L9Low primary circuit flow rate detected by flow switch (flow switches 1, 2, 3)See Action for L3. If the flow switch itself does not work, replace it. Caution: The pump valves may be hot, please take care.
LCBoiler circulation water temperature overheat protectionCheck if the setting temperature of the Boiler for heating exceeds the re- striction. (See the manual of the thermistors "PAC-TH011HT-E")
Flow rate of the heating circuit from the boiler may be reduced. Check for
• water leakage,
• strainer blockage
•water circulation pump function.

LDBoiler temperature thermistor (THWB1, THWB2) failureCheck resistance across the thermistor.
LEBoiler operation errorSee Action for L8. Check the status of the boiler.
LHBoiler circulation water freeze protectionFlow rate of the heating circuit from the boiler may be reduced. Check for
• water leakage
• strainer blockage
•water circulation pump function.
LLSetting errors of Dip switches on FTC4 control boardFor boiler operation, check that Dip SW1-1 is set to ON (With Boiler) and Dip SW2-6 is set to ON (With Mixing Tank).
For 2-zone temperature control, check Dip SW2-7 is set to ON (2-zone) and Dip SW2-6 is set to ON (With Mixing Tank).
JOCommunication failure between FTC4 and wireless receiverCheck connection cable for damage or lose connections.
P1Thermistor (Room temp.) (TH1) failureCheck resistance across the thermistor.
P2Thermistor (Ref. liquid temp.) (TH2) failureCheck resistance across the thermistor.
P6Anti-freeze protection of plate heat exchangerSee Action for L3. Check for correct amount of refrigerant.
J1 -J8Communication failure between wireless receiver and wireless remote controllerCheck wireless remote controller's battery is not flat. Check the pairing between wireless receiver to wireless remote controller. Test the wireless communication. (See the manual of wireless system)
EO - E5Communication failure between main controller and FTC4Check connection cable for damage or loose connections.
E6-EFCommunication failure between FTC4 and outdoor unitCheck that the outdoor unit has not been turned off. Check connection cable for damage or loose connections. Refer to outdoor unit service manual.
E9Outdoor unit receives no signal from indoor unit.Check both units are switched on. Check connection cable for damage or loose connections. Refer to outdoor unit service manual.
U*, F*Outdoor unit failureRefer to outdoor unit service manual.

Mitsubishi Heavy Industries FDC280KXZE1 air conditioner error codes

Remote control error code7-segment displayName of inspectionClassification
El-Remote control communication errorCommunication error
E2-Duplicated indoor unit addressAddress setting error
E3-Outdoor unit signal line errorAddress painng setting error
E5-Communication error during operationCommunication error
E6-Indoor heat exchanger temperature thermistor anomaly (ThI-R)Thermistor wire breakage
El-Indoor return air temperature thermistor anomaly (Thl-A)Thermistor wire breakage
E9-Drain troubleSystem error
E10-Excessive number of indoor units (more than 17 units) by controlling one remote controlCommunication error
Ell-Address setting error between master and slave indoor unitsAddress setting error
E12-Address setting error by mixed setting methodAddress setting error
E16-Indoor fan motor anomaly (FDT, FDTC, FDTW, FDTS, FDU, FDUM, FDK, FDUT71, FDFW series)DC fan motor error
E18-Address setting error of master and slave indoor unitsAddress setting error
E19-Indoor unit operation check drain motor check mode anomalySetting error
E20-Indoor fan motor speed anomaly (FDT, FDTC, FDTW, FDTS, FDU, FDUM, FDK, FDU 171, FDFW series)DC fan motor error
E21-Detective panel switch operation (FDT)Panel switch error
E28-Remote control temperature thermistor anomaly (The)Thermistor wire breakage
E31E31Duplicated outdoor unit address No.Address setting error
E32E32Open L3 Phase on power supply at primary sideSite setting error
E36E36-1,2Discharge pipe temperature error (Tho-D 1, D2)System error
E37E37-1.2 E37-4, 5 E37-5, 6Outdoor heat exchanger temperature thermistor (Tho-R) and subcooling coil temperature thermistor (Tho-SC, -H) anomalyThermistor wire breakage
E38E38Outdoor air temperature thermistor anomaly (Tho-A)Thermistor wire breakage
E39E39-1.2Discharge pipe temperature thermistor anomaly (Tho-D 1, D2)Thermistor wire breakage
E40E40High pressure anomaly (63H1-1, 2 activated)System error
E41(E51)E41 (E51)-l,2Power transistor overheatSystem error
E42E42-1,2Current cut (CM1, 2)System error
E43E43-1, E43-2Excessive number of indoor units connected, excessive total capacity of connectionSite setting error
E44E44-1,2Liquid flooding anomaly (CM 1,2)System error
E45E45-1,2Communication error between inverter PCB and outdoor control PCBCommunication error
E46E46Mixed address setting methods coexistent in same networkAddress setting error
E48E48-1, E48-2Outdoor DC fan motor anomalyDC fan motor error
E49E49Low pressure anomalySystem error
E53/E55E53/E55-1, 2Suction pipe temperature thermistor anomaly (Tho-S), Under-dome temperature thermistor anomaly (Tho-Cl, C2)Thermistor wire breakage
E54E54-1, E54-2High pressure sensor anomaly (PSH) Low pressure sensor anomaly (PSL)Thermistor wire breakage
E56E56-1,2Power transistor temperature thermistor anomaly (Tho-Pl, Tho-P2)Thermistor wire breakage
E58E58-1,2Anomalous compressor by loss of synchronismSystem error
E59E59-1,2Compressor startup failure (CM1, 2)System error
E61E61-1,2Communication error between the master unit and slave unitsSystem error
E63E63Emergency stopSite setting error

Mitsubishi Heavy Industries SRK20ZJ-S air conditioner error codes

No.Remote controller displayDescription of trouble
1NoneOperates but does not cool.
2NoneOperates but does not heat.
3NoneEarth leakage breaker activated
4NoneExcessive noise/vibration (1/3)
5NoneExcessive noise/vibration (2/3)
6NoneExcessive noise/vibration (3/3)
7NoneLouver motor failure
8NonePower supply system error (Power supply to indoor control PCB)
9NonePower supply system error (Power supply to remote controller)
10INSPECT I/UINSPECT IAJ (When 1 or 2 remote controllers are connected)
11INSPECT I/UINSPECT I/U (Connection of 3 units or more remote controllers)
12WAITCommunication error at initial operation
13ElRemote controller communication circuit error
14E5Communication error during operation
15E6Indoor heat exchanger temperature thermistor anomaly
16E7Return air temperature thermistor anomaly
17E8Heating overload operation
18E9Drain trouble
19E10Excessive number of connected indoor units (more than 17 units) by controlling with one remote controller
20EI6Indoor fan motor anomaly
21EI9Indoor unit operation check, drain motor check setting error
22E28Remote controller temperature thermistor anomaly
23E35Cooling overload operation
24E36Discharge pipe temperature error
25E37Outdoor heat exchanger temperature sensor anomaly
26E38Outdoor air temperature sensor anomaly
27E39Discharge pipe temperature sensor anomaly
28E42Current cut
29E47Active filter voltage error
30E48Outdoor fan motor anomaly
31E51Power transistor anomaly
32E57Insufficient refrigerant amount or detection of service valve closure
33E58Current safe stop
34E59Compressor startup failure
35E60Anomalous compressor rotor lock