Mitsubishi AC Error Codes List (Troubleshooting Guide)

Mitsubishi Electric Corporation was established in 1921 and worked its way to becoming a leading multinational electrical equipment and electronics manufacturer. With its headquarters in Tokyo, there was a time the company only focused on elevators, escalators, and high-end appliances such as air conditioners. While the company has grown, these three remain to be their top candidates.

When it comes to air conditioning the company offers ac systems such as room air conditioners, package air conditions, VRF systems, Ventilators, air curtains, and so on. Along with endless home and commercial appliances that start with toasters and ends with elevators and moving walks. With its main focus on air conditioners, Mitsubishi is one of the leading designers, manufacturers, and providers in the world. Yet, there are times when customers find themselves baffled by a random code on their appliance.

To help you out we have listed down some of the most common error codes for Mitsubishi Air conditioners. Start by noting down the error code, and match it using the list below. Once you have the error code you can understand the main issue with your Mitsubishi air conditioner, and draw out a solution that works to your advantage.

Contents

Mr Slim P Series (A)

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 – Meaning and Solution

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
ho	-For about 2 minustes following power-on, operation of the remote controller is not possible deu to system start-up. - Connector for the outdoor unit's protection device is not connected. -Reserve or open phase wiring for the outdoor unit's power terminal block (L1,L2,L3). -Incorrect wiring between indoor and outdoor units (incorrect polarity of S1,S2,S3). -Remote controller wire short.
FFFF	No unit. Buzzer sound: Triple beep. Operation Led: No lit.
U0-UP	Outdoor unit error.
F1-FA	Outdoor unit error.
E0-E5	Signal error between remote controller and indoor units.
E6-EF	Communication error between indoor and outdoor units.
--	No alarm history.

Mr Slim P Series (K)

Mitsubishi Electric Fault Codes – Solutions

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

Multi City VRF

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.

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

Cassette AC

Alarm Codes	Solutions
P1	Intake sensor error
P2	Pipe (TH2) sensor error
P9	Pipe (TH5) sensor error
E6,E7	Indoor/outdoor unit communication error
P4	Drain sensor error/Float switch connector (CN4F) open
P5	Drain pump error
PA	Forced compressor stop (due to water leakage abnormality)
P6	Freezing/Overheating protection operation
EE	Communication error between indoor and outdoor units
P8	Pipe temperature error
E4,E5	Remote controller signal receiving error
Fb	Indoor unit control system error (memory error, etc.)
PL	Refrigerant circuit abnormal
E0,E3	Remote controller transmission error
E1,E2	Remote controller control board error
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 operated/ insufficient refrigerant
U1,Ud	Abnormal high pressure (63H operated)/Overheating protection operation
U5	Abnormal temperature of heat sink
U8	Outdoor unit fan protection 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

Ecodan

Ecodan air source heat pumps use 1kW of electrical energy input and take 2.2kW of low temperature renewable heat energy from the air, producing a high efficient 3.2kW heat energy output. This heats refrigerant in the system which in turn heats water for domestic hot water and space heating.

Fault Codes	Problem
F3	Low pressure switch failure - check connection on the board and continuity of switch
F5	High pressure switch failure - check connection onto board and continuity of switch
F9	Both pressure switch contacts are open at the same time - check connection onto board and continuity of switch and for a potential board failure
EA	Mis-wiring fault between FTC and Ecodan - check S1,S2,S3 also check voltages and comms
EB	Mis-wiring fault between FTC and Ecodan - Check S1,S2,S3 also check voltages and comms
EC	Unit cannot finish start up process - generally caused by a comms fault
U1	Ecodan high pressure fault - mainly caused by incorrect water flow rates - check with flow setter
U2	Ecodan high compressor discharge temperature - mainly caused by refrigerant shortage or dirty condenser
U3	Ecodan discharge thermistor problem - mainly caused by TH4 discharge thermistor - open/close circuit
U4	Open or close circuit Ecodan thermistors (TH3, TH32, TH33, TH6, TH7, TH8) - open or close circuit or disconnected from main board
U5	Inverter heat sink overheat protection (W50 and W85 models 77°C, HW140 model 95°C - reduced air flow through Ecodan - faulty fan motor
U6	Inverter/Compressor over current - system indicates possible IPM error
U8	Ecodan fan motor problem - mainly caused by DC fan motor being disconnected, connected or obstructed with the power on or possible main board fault
U9	Over voltage or under voltage - mainly caused by either CN2 or CN5 loose or disconnected or decrease of mains power supply
UD	Overheat protection TH3 ≥ 70°C or 63HS ≥ 70°C saturation temperature
UF	Compressor over current/Compressor lock - occurs within 30 seconds of compressor start
UH	Abnormal running current - < 1A or > 40A detected during operation - check CN5 connections
UL	Open circuit (63L )
UP	Over current detected after 30 seconds of operation - do an inverter test to determine outputs balanced
E0	Transmitting Error PAR W21 - check refrigerant address on SW1 of Ecodan
E1	Faulty controller
E3	Transmitting Error (PAR W21) - check refrigerant address on SW1 of Ecodan
E4	Receiving Error (PAR W21) - check refrigerant address of SW1 on Ecodan
E5	Receiving Error (PAR W21) - check refrigerant address of SW1 on Ecodan
E6	Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
E8	Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
E9	Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
EF	Non-defined error code - noise interference - power down Ecodan for 30 seconds then switch back on
ED	Serial communication fault between Ecodan main board and Ecodan inverter board - mainly due to loose CN2 or CN5 cable
P1	Flow temp sensor fault - TH1 not connected, short or open circuit
P6	Over heating at heat exchanger - lack of water flow, air in the system, flow rate incorrectly set, blockage or pump problem
P8	No temp change at plate heat exchanger - problem with flow rate (too high) - incorrect sizing of system
P9	TH5 Fault - TH5 not connected, short or open circuit, FTC not configured for heating only
PE	Inlet water temp fault - TH32 is below 10°C whilst compressor is in operation - possible thermistor out of range, short of gas, incorrect sizing of radiator or problem in the water circuit (blockage, pump failure etc)

Hot Water Heat Pumps PWFY Series

12.5kW Hot Water Module. Flexibility to create very large systems. Can be installed in conjunction with City Multi VRF air conditioning. Available in one size: PWFY-P100VM-E-BU (12.5kW heating) which is modular to allow creation of larger solutions. Sanitary water heating has suitable applications in: hotels and motels, apartments, commercial kitchens and laundries, office buildings, food processing industry, heat recovery from air conditioning systems into sanitary water storage, and direct sanitary water heating is also possible.

Fault Codes	Problem
403	Comms fault between boards - check between control board an inverter board
403	Comms fault between boards - check between control board an fan board
1102	High compressor discharge temperature - discharge temp has exceeded 115°C or more - check if short of refrigerant or discharge thermistor
1301	Low pressure fault - low pressure sensor sensing less than 1 bar immediately before starting
1302	High pressure fault - check system pressure exceded 32.3 bar, check high pressure sensor (63HS) against gauge pressure
2000	Pump interlock error - pump interlock open whilst system in operation
2134	Abnormal water temperature (TH6) has exceded 85°C
2135	Water source heat exchanger frozen (TH6) or (TH8) reading 2°C
4102	Open phase fault - check power supply and noise filter for loss of phase, check wiring and fuses
4115	Power supply abnormal - check power, fuses, connections and PCB
4220	Low inverter board BUS voltage - less than 200Vdc is detected during in inverter operation - check mains supply
4220	Bus voltage error PAM damage - replace the inverter board
4220	High bus voltage Vdc>380v - check power supply and possible faulty inverter board
4220	Replace inverter board
4230	High temperature (85°C) on heat sink on inverter - check for blockages in air duct, failure of INV fan failure of INV fan or failure of thermistor (THHS)
4250	Over current protection - inverter IPM problem or compressor lock - check inverter balance
4250	ACCT sensor over current detection 34.5A peak or 16A rms is detected - check the compressor for failure, or possible inverter board failure
5102	Thermistor TH22 failure
5103	Thermistor TH13 or TH23 failure
5104	Thermistor TH11 failure
5106	Thermistor TH6 failure
5108	Thermistor TH8 failure
5110	Thermistor THHS failure
5201	High pressure sensor fault - check the system pressure is >1 bar, check the operation of 63HS high pressure transducer
5202	Pressure sensor fault
5301	Current sensor fault, ACCT or DCCT - check inv. error details
5301	Low output current <1.5A rms whilst the inverter is in operation

Packaged Hot Water Heat Pump CAHV

45kW Packaged Hot Water Heat Pump. Can be combined to max. 70kW. “Flash-injection Circuit”, which is designed for our ZUBADAN CITY MULTI (air conditioning system for cold regions), is mounted in our new Hot Water Heat Pump. By utilizing our advanced “Flash-injection Circuit” and the latest high-efficiency compressor, Hot Water Heat Pump provides hot water upto 70°C, and produces less capacity drop at low outdoor temperature.

Error Codes	Problem
AFSA	Water supply cut-off (flow switch has been triggered) - check flow switch and wiring
AHP1	High pressure fault - check water flow, possible high pressure sensor fault LEV fault
AdSH	Compressor crank case temperature of 10°C or less for 40 minutes while compressor in operation - check for possible failure of fan motor, low pressure sensor, compressor shell thermistor, high pressure sensor, discharge thermistor (TH1 TH5), LEV or SV2
1303	Low pressure protection low pressure below 6 bar within 30 sec of start up - possible failure of LP sensor, air inlet thermistor fault (TH4 TH8), suction temperature (TH2 TH6), LEV bypass check valve
1103	Compressor shell bottom temperature exceeded 80°C detected whilst compressor running
5109	Compressor shell thermistor faulty (TH3 TH6), LEV failure
5110	Outside temperature thermistor fault - check TH9
5112	Water inlet temperature - check TH10 main circuit
5111	Water inlet temperature - check TH12 sub circuit
5113	Outlet water temperature - check TH11 main circuit
5103	Outlet water temperature - check TH12 sub circuit
5107	Compressor shell temperature - check TH3 main circuit
5101	Compressor shell temperature - check TH7 sub circuit
5105	Discharge temperature - check TH1 main circuit
5102	Discharge temperature - check TH5 sub circuit
5106	Inlet temperature - check TH2 main circuit
5104	Inlet temperature - check TH6 sub circuit
5108	Air to refrigerant heat exchanger inlet temperature - check TH4 main circuit
5114	Air to refrigerant heat exchanger inlet temperature - check TH8 sub circuit
5115	Common return water when using multiple outdoors - check TH14
5117	Common return water when using multiple outdoors - check TH15
5118	High pressure sensor or high pressure fault - check 63HS sensor or 63H (hp switch)
7113	Low pressure sensor low or low pressure fault - check 63LS
7117	Model setting error 1 - mis-set switch
4115	Model setting error 2 - faulty Z21 resistor
A471	Power supply frequency fault - power supply frequency is not 50Hz or 60Hz
1104	Discharge temperature fault - 120°C detected during compressor operation - check water flow, pump, high pressure sensor fault or LEV fault
AC61	Power supply fault - check transmission power supply or if PCB faulty

MR Slim Operation Light Blinking

Mitsubishi Air Conditioner Operation Light Flashing – Fix it

Flashing of POWER lamp indicates abnormalities. Before taking measures, make sure that the symptom reappears for accurate troubleshooting. Self check table

When the indoor unit has started operation and the above detection method has detected an abnormality (the first detection after the power ON), the indoor electronic control P.C. board turns OFF the indoor fan motor with OPERATION INDICATOR lamp flashing.

Indicator lamp	Solution
POWER lamp flashes. 0.5-second ON	Mis-Wiring or serial signal. Outdoor unit does not operate. When the serial signal form the outdoor unit is not received for a maximum of 6 minutes.
POWER lamp lights up	Out door control system. Outdoor unit does not operate. When it cannot properly read data in the nonvolatile memory of the inverter P.C. board or the outdoor electronic control P.C. board. Check the blinking pattern of the LED on the inverter P.C. board or the outdoor lectronic control P.C. board.
POWER lamp flashes. 2-time flash	Indoor coil thermistor. Room temperature thermistor. Indoor unit and outdoor unit do not operate. When the indoor coil or the room temperature thermistor is short or open circuit.
POWER lamp flashes. 3-time flash	Indoor fan motor. Indoor unit and outdoor unit do not operate. When the rotational frequency feedback signal is not emit during the indoor fan operation.
POWER lamp flashes. 5-time flash	Out door power system. Indoor unit and outdoor unit do not operate. When it consecutively occurs 3 times that the compressor stops for overcurrent protection or start-up failure protection witth in 1 minute after start-up.
POWER lamp flashes. 6-time flash	Outdoor thermistors. Indoor unit and outdoor unit do not operate. When the outdoor thermistors short or open circuit during the compressor operation.
POWER lamp flashes. 7-time flash	Out door control system. Indoor unit and outdoor unit do not operate. When it cannot properly read data in the nonvolatile memory of the inverter P.C. board or the outdoor electronic control P.C. board.
POWER lamp flashes. 14-time flash	Other abnonmality. Indoor unit and outdoor unit do not operate. An abnormality other than above mentioned is deteced. Confirm the abnormarity in detail using the failure mode recall function.

Split AC Timer Light Blinking

Trouble	Contents
3 blinking-1 blinking	Abnormality of comp. surface thermistor (TH32) and discharging temperature (TH4)
3 blinking-2 blinking	Abnormal high pressure (High pressure switch 63H operated.)
3 blinking-3 blinking	Abnormality of outdoor fan motor rotational speed. Protection from overheat operation(TH3).
3 blinking-4 blinking	Compressor overcurrent breaking (Start-up locked). Compressor overcurrent breaking. Abnormality of current sensor (P.B.). Abnormality of power module.
3 blinking-5 blinking	Open/short of discharge thermistor (TH4) and comp. surface thermistor (TH32). Open/short of outdoor thermistors (TH3, TH6, TH7 and TH8).
3 blinking-6 blinking	Abnormality of heatsink temperature
3 blinking-7 blinking	Abnormality of voltage
4 blinking-1 blinking	Abnormality of room temperature thermistor (TH1). Abnormality of pipe temperature thermistor /Liquid (TH2). Abnormality of pipe temperature thermistor/Condenser-Evaporator.
4 blinking-2 blinking	Abnormality of drain sensor (DS) Float switch(FS) connector open. Indoor drain overflow protection.
4 blinking-3 blinking	Freezing (cooling)/overheating (heating) protection
4 blinking-4 blinking	Abnormality of pipe temperature

Mitsubishi Split Air Conditioner Timer Light Blinking

Aircon RedLINK Codes

Error Codes	Meaning
E0 27	Verify device temperature is within operating range. If within range for at least 30 minutes and problem persists, replace Remote Controller.
E0 91	Communication was established between wireless receiver and the indoor unit, but communication has been lost for 10 minutes. Check cable connection. Try replacing the cable.
E1 29	Attempting to connect incompatible wireless devices.
E1 34	Low signal strength. Move wireless device to a different location and try again.
E1 38	Make sure Connect light on wireless receiver is flashing and you are 2+ feet away from wireless receiver.
E1 54	Indoor unit does not support wireless receiver.