Mitsubishi Air Conditioner Error Codes

Mitsubishi Electric Fault Code Check List Index:

Mitsubishi Air Conditioning Error Codes

1. Mitsubishi Mr Slim P Series (A) Error Codes
2. Mitsubishi Mr Slim P Series (K) Error Codes
3. Mitsubishi Multi City VRF Error Codes
4. Mitsubishi Ecodan Error Codes
5. Mitsubishi PWFY Series Error Codes
6. Mitsubishi CAHV Error Codes
7. Operation Light Flashing
8. Troubleshooting

1-Mitsubishi Electric Mr Slim P Series (A) Error Codes

Mr. Slim P-Series ductless heat pumps and air conditioners are compact yet powerful, offering unrivaled energy efficiency and design flexibility. Their advanced technology has been designed and tested to withstand the extremes of the Canadian climate in order to deliver a reliable and proven climate control system that you can trust all year round. With a variety of models to choose from, there’s a P-Series solution for any commercial application.

Mitsubishi Mr. Slim Air Conditioner Error Codes

Fault Codes	Problem
A0	Duplicate address - Lossnay units attached with the same address - change addresses and reset the units power
A2	Hardware error of transmission processor (Lossnay) - check comms wiring, and for possible Lossnay board fault
A3	Line busy no data could be transmitted for 8 minutes - check A- M-Net connections (TB7 and TB3)
A6	Communication error with communication processor - Lossnay address not transmitted - check M-Net voltage
A7	No ACK signal - check A- M-Net wiring, range of transmission wiring exceeded or if faulty A- M-Net converter
A8	M-Net no response - check A- M-Net wiring, range of transmission wiring exceeded, faulty A- M-Net converter or if incorrect wire used for M-Net connection
EA	Mis-wiring/loose inter-connecting cables. Noise interference
EB	Mis-wiring/loose interconnecting cables. Noise interference. Wrong cable size/spec
EC	Start-up time over. The unit has failed to initialise after power up. Noise interference. Wrong cable size/spec
ED	Serial communication error. Comms error between boards on outdoor unit caused by M-Net interface board incorrectly fitted
EF	Non-defined error code. Noise interference - power down outdoor unit for 30 seconds then switch back on
E0	Remote controller communication error - check wiring, connections and comms voltage. Also check Master/Slave settings if multiple systems are connected
E1	Remote controller issue - if grouped, check addressing. If twinned, check wired to master indoor only
E2	Remote controller issue - if grouped, check addressing. If twinned, check wired to master indoor only
E3	Remote controller issue - not transmitting - if grouped, check addressing. If twinned check wired to master indoor only
E4	Remote controller issue - not receiving - if grouped, check addressing. If twinned, check wired to master indoor only
E5	Remote controller issue - not receiving - if grouped, check addressing. If twinned, check wired to master indoor only
E6	Indoor/outdoor communication error, mainly caused by outdoor unit being powered up before indoor unit. Drain pump being wired into S1 and S2 causes interference
E7	Comms fault between I/C and O/C - check for condensate pump at I/C, reset power to O/C, check 12/24Vdc on S2 and S3 possible I/C board failure
E8	Comms failure indoor to outdoor (S2/S3) - check pumps wired in, check indoor isolator and re-power in the correct sequence i.e. indoor then outdoor
E9	Comms failure indoor to outdoor (S2/S3) - check pumps wired in, check indoor isolator and re-power in correct sequence i.e. indoor then outdoor
FA	51CM connector open - check thermal relay for disconnection or contact failure. Possible defective board
F1	Reverse phase detection - check power supply, try swapping 2 phases round. Possible defective board
F2	L3 phase open - check power supply, also check for open circuit protection devices
F3	63L open - check low pressure switch for disconnection or contact failure. Possible defective board
F4	49C open - compressor inner thermostat for open circuit or contact failure
F5	63H open - check high pressure switch for disconnection or contact failure. Possible defective board
F7	Phase detection circuit fault - faulty outdoor board
F8	No input detected at outdoor unit - outdoor board defective
F9	Two or more protection devices are open - check protection devices for disconnection or contact failure
P1	Return air thermistor fault (TH1) - check if TH1 disconnected or open or close circuit
P2	Liquid pipe thermistor fault (TH2) check if TH2 disconnected or open or close circuit
P4	Drain sensor fault - DS open or close circuit
P5	High condensate level - drain pump failure or blockage in the drain
P6	Freezing/Overheating of indoor unit heat exchanger - mainly caused by reduced air flow through indoor coil. Dirty filters. Fan motor problem. Blockage
P8	Abnormal pipe temperature - mainly caused by refrigerant leakage. Possibility that the thermistor mounted incorrectly
P9	TH5 condenser/evaporator thermistor open/close circuit. Disconnected from the board
U1	High pressure trip - outdoor fan failure, blocked coil, blockage in the system, blocked filters on indoor in heating etc
U2	High discharge temperature - compressor over heating due to lack of refrigerant, faulty thermistor, high ambient running conditions. Can also be caused by 49C (comp inner thermostat or external Klixon ) tripping
U3	Discharge thermistor fault
U4	Outdoor thermistor fault
U5	Inverter heat sink temperature too high (TH8) - check for lack of air flow around heat sink, no silicone paste, faulty thermistor (temperature can be read from service tool (or PAR21 on power inverter model))
U6	Compressor over current - carry out inverter output test and electrical checks to the compressor
U7	Low discharge superheat - check TH4 reading is correct. Check LEV operations

2-Mitsubishi Electric Mr Slim P Series (K) Error Codes

Mitsubishi Electric Fault Codes

Mr. Slim P-Series is the ductless solution for demanding environments that require an efficient and reliable heating or cooling system. P-Series ductless systems are stylish, compact, and more attractive than traditional systems. Advanced technology also means your Mr. Slim ductless system will run more efficiently than a conventional unit, saving you from rising energy costs.

Fault Codes	Problem
EO	System transmission error - check for possible comms fault between I/C and R/C, could also be incorrect group or master/slave settings (check CN40, SW2 and SW6)
P1	TH1 fault - check return air thermistor (6.4K_ @ 20°C)
P2	TH2 fault - check coil/pipe thermistor (6.4K_ @20°C)
P3	System transmission error - check for possible comms fault between I/C and R/C, could also be incorrect group or master/slave settings (check CN40, SW2 and SW6)
P4	Drain sensor fault - check drain sensor resistance, connection and continuity
P5	Drain fault - unit has detected high condensate - check for blockage in drain or tray, pump failure or sensor fault
P6	Frost protection in cooling/Overheat protection in heating - detected by indoor coil sensor - general causes are lack of air flow or refrigerant charge problem
P7	System error - address setting fault - check CN40 SW2 and SW6. Potential board issue
P8	Abnormal pipe/coil temperature - no temperature change at indoor unit after 9 minutes of operation. General causes are outdoor unit tripped, problem with refrigerant charge or lack of air flow at the indoor unit. TH2 faulty or not mounted correctly
LD1	Reverse phase on mains supply - change phases around, check for potential board problem
LD2	Component open circuit - check CH, 52C, 21S4, SV, 63H and 26C for open circuit or disconnected
LD3	Outdoor coil thermister is open or short circuit may be disconnected or outdoor board fault
LD4	63H high pressure switch open - investigate high pressure causes, 63H switch disconnected
LD5	51CM overcurrent relay open - compressor locked or pulling too much current - check power supply
LD6	26C thermal switch open - check if refrigerant level low or if 26C is disconnected
LD7	Overheat protection - coil temp has exceeded 67°C - reduced airflow through condenser - check for fan motor problem or thermistor problem
LD8	Input circuit of outdoor board - replace the outdoor board

3-Mitsubishi Multi City VRF AC Error Codes

The CITY MULTI S series (for small applications) and Y series (for large applications) make use of a two-pipe refrigerant system, which allows for system changeover from cooling to heating, ensuring that a constant indoor climate is maintained in all zones.

Mitsubishii Multi City VRF AC Error Codes

Error Codes	Problem
403	Comms fault between boards - check inverter error detail for which 2 boards, check transformer, bus voltage and inter-connecting cables
900	Lossnay unit in test run
1102	High compressor discharge temperature. Discharge temperature has exceeded 110°C or more. Short of refrigerant. Discharge thermistor
1111	Low pressure/temperature fault - check thermistors (TH2, TH3, TH4), gas charge, indoor fan, heat exchanger and filter
1112	Low pressure/temperature fault - check thermistors (TH2, TH3, TH4), gas charge, indoor fan, heat exchanger and filter
1113	Low pressure/temperature fault - check thermistors (TH2, TH3, TH4), gas charge, indoor fan, heat exchanger and filter
1202	Preliminary fault to 1102
1204	Preliminary heat exchanger gas temperature sensor fault - check thermistors 10a and 10b
1205	Preliminary thermistor fault (TH5)
1211	Preliminary thermistor fault (TH2)
1214	Preliminary thermistor fault (THHS)
1216	Preliminary thermistor fault (TH7)
1217	Preliminary thermistor fault (TH8)
1219	Preliminary thermistor fault (TH9)
1221	Preliminary thermistor fault (TH6)
1243	Preliminary thermistor fault (TH10)
1301	Low pressure fault (63L operation) low pressure sensor sensing less than 1 bar immediately before starting
1302	High pressure fault - check pressure in system for more than 29 bar (R407c) 38 bar (R410A). Check high pressure sensor against gauge pressure
1368	Pressure sensor fault (PS1) at BC - compare pressure reading on SW1 on O/C
1370	Pressure sensor fault (PS3) at BC - compare pressure reading on SW1 at O/C
1402	Preliminary fault to 1302
1500	System overcharge. Abnormal low compressor superheat - discharge thermistor TH4
1501	High compressor shell temp - check for shortage of gas, insufficient indoor index running (comms room units)
1505	Suction pressure abnormal - generated by low pressure sensor detecting a vacuum - check for blockage, closed valve or sensor fault
2500	Detecting lack of water flow on a water circuit
2502	I/C has water level in drip tray, when the unit was running in cooling (temperature sensors - check for open or closed circuit and operation of pump)
2503	I/C has water level in drip tray when the unit was running in cooling (float sensor - check for closed circuit on float switch and operation of pump)
2600	Water leak from humidifier
4100	Compressor over current protection on Mr Slim with M-net interface - check inverter or compressor
4101	Compressor over current protection on Mr Slim with M-net interface - check inverter or compressor
4102	Open phase fault - check power supply and noise filter for loss of phase, check wiring and fuses
4103	Reverse phase fault - check phase rotation, loss of phase through the noise filter, fuse blown and high pressure switch open at power on
4106	Transmission power supply fault - check wiring, high current, incorrect voltage on transmission line and/or M-Net board
4108	Over current protection on DOL compressor - check power supply, contactor and compressor
4115	Power supply abnormal - check power, fuses, connections and PCB
4116	Fan motor abnormal - check fan motor and board (relates to indoor unit or Lossnay unit)
4124	Thermal switch (49C) open circuit on Mr Slim on M-Net - reset and check pressures and air flow
4210	Compressor over current problem - check inverter balance. Compressor and inverter
4220	Low inverter board BUS voltage. Less than 289VdcDC is detected. - check mains supply
4225	Low DC voltage on Vdc on fan inverter - check CNVdc for 300Vdc on diode stack and check mains power supply to outdoor unit
4230	High temperature on heat sink on inverter - check for blockages in air duct, failure of INV fan or failure of thermistor
4235	Fan inverter heat sink overheat protection. Reduced airflow through heat sink. Fan motor problem. THHS thermistor problem
4240	Over current protection. If high current is detected for more than 10 minutes - check inverter balance. Reduced airflow through heat sink
4245	Over current protection. Possible ACCT current sensor fault. Should read 280 ohms between pins 1 & 2 and across pins 3 & 4
4250	Over current protection. Inverter IPM problem. Compressor lock - check inverter balance
4255	Inverter cooling fan problem - if high static fan is used then check that SW3-9 is on
4260	Preliminary inverter heat sink overheat protection. Reduced airflow through heat sink. Fan motor problem. THHS thermistor problem
5101	Thermistor fault at indoor/outdoor unit - check fault code address
5102	Thermistor fault at indoor/outdoor unit - check fault code address
5103	Thermistor fault at indoor/outdoor unit - check fault code address
5104	Thermistor fault at indoor/outdoor unit - check fault code address (indoor fault - check SW7-3 is off)
5105	TH5 open/short circuit - check if the TH is disconnected from the board
5106	TH6 open/short circuit - check if the TH is disconnected from the board
5107	TH7 open/short circuit - check if the TH is disconnected from the board
5108	TH8 open/short circuit - check if the TH is disconnected from the board
5109	TH9 open/short circuit - check if the TH is disconnected from the board
5110	TH10 open/short circuit - check if the TH is disconnected from the board
5111	BC box thermistor error - TH11 open/short circuit, disconnected from board/pipe
5112	BC box thermistor error - TH10 open/short circuit, disconnected from board/pipe
5113	BC box thermistor error - TH open/short circuit, disconnected from board/pipe
5114	BC box thermistor error - TH open/short circuit, disconnected from board/pipe
5115	BC box thermistor error - TH15 open/short circuit, disconnected from board/pipe
5116	BC box thermistor error - TH16 open/short circuit, disconnected from board/pipe
5201	Pressure sensor fault outdoor unit/BC box - check fault code address/SW1 pressure sensor readings
5202	Pressure sensor fault (PS2) in the BC box
5203	Pressure sensor fault (PS3) in the BC box
5300	A-Control UH fault - see Mr Slim fault code list
5301	Current sensor fault, ACCT or DCCT - check inv. error details
5401	Temperature sensor fault - check CN30 for humidity sensor
5701	Loose float switch connector - check switch, check CN4F on indoor unit
6201	TB7 transmission line communication error - check for voltage abnormality/short
6202	Transmission processor hardware error - check for noise/short on M-Net cable
6600	Repeat address fault - two or more units are assigned the same address - correct the repeated address
6601	Polarity setting error - no voltage or short circuit on the m-net transmission line
6602	Hardware error of transmission processor. Noise interference. Polarity problem on TB7
6603	Bus circuit busy - check if indoor unit, Lossnay unit or anything else has been wired into TB7, instead of TB3
6607	Communication issue - no response back from unit whilst system is operational
6608	Communication error - loss of voltage or noise entering the transmission line
6700	K control communication error - R22 type unit connected onto M-Net circuit comms error
6701	K control communication error - R22 type unit connected onto M-Net circuit comms error
6702	K control duplicate address error - two or more R22 type units connected onto M-Net circuit with the same address
6750	K control communication error - R22 type unit connected onto M-Net circuit comms error
6751	R22 R/A thermistor fault (P1)
6752	R22 frost protection at I/C (P6)
6753	Comms fault between O/C and I/C
6754	R22 drain fault (P5)
6755	R22 drain fault (P5)
6756	R22 frost protection at I/C (P6)
6757	System error
6758	Comms fault between I/C and O/C
6761	R22 R/A thermistor fault (P1)
6762	R22 TH2 fault check resistance (P2)
6763	R22 Comms fault between I/C and O/C
6764	R22 drain fault (P4)
6765	R22 drain fault (P5)
6766	R22 frost protection at I/C (P6)
6767	R22 comms fault between I/C and O/C
6771	K abnormality - high pressure abnormality or low pressure abnormality
6772	K abnormality - inner thermostat function, discharge temperature abnormality, shell thermostat function, over current protection
6773	K abnormality - radiator plate thermostat function
6774	K abnormality - outdoor thermistor abnormality
6775	K abnormality - pressure sensor abnormality, indoor/outdoor communication error
6776	K abnormality - over current shut-off
6777	K abnormality - system error
6778	K abnormality - normal
6779	K abnormality - refrigerant overcharge, abnormal voltage, abnormal CT sensor
6830	Comms fault between I/C and R/C check connections to MA R/C and check for 12Vdc check R/C not set sub controller
6831	MA R/C communication fault - check connections on TB15 or that the controller was removed while the I/C was powered
6832	MA controller comms fault - check cable length no bigger than 500m, check connection and type of cable used, check R/C not set sub on field settings
6833	MA controller comms fault check cable length no bigger than 500m, check connection and type of cable used, check R/C not set sub on field settings
6834	MA Controller comms fault - check cable length no bigger than 500m, check connection and type of cable used, check R/C not set sub on field settings
6840	A-Control E6/E8 fault - see Mr Slim fault code list
6841	A-Control E7/E9 fault - see Mr Slim fault code list
6844	A-Control EA fault - see Mr Slim fault code list
6845	A-Control Eb fault - see Mr Slim fault code list
6846	A-Control EC fault - see Mr Slim fault code list
7100	Over capacity - (R2 150% index exceeded) (Y 130% index exceeded)
7101	Capacity setting error - SW2 set wrong on indoors, SW5 on YHMA outdoor, (SW3-10 on older kit)
7102	Error in number of connected units - loss of M-Net voltage (short or break), no power to BC, wrong SW5 setting on box, wrong box type
7105	Address setting error - OC or BC addressed wrong
7106	Attribute setting error - SW3-1 setting on a GUF
7107	Port setting error - check if too much capacity on a single port, wiring SW2 setting, wrong SW14 setting or wrong units on a box when using multiple boxes
7110	Check SW5-7 is correctly set
7111	Remote control sensor fault - SW1 - 1 on and no controllers fitted or faulty remote controller
7113	Function setting error - wrong SW5 setting or wrong resistors fitted on YHM-A
7117	Model setting error - SW5 set wrong or wrong resistors in
7130	Incompatible equipment on M-Net - check split with MAC 399 wired onto the TB5 line TB5 line, not the TB7