Mitsubishi Ecodan air conditioner fault codes

Fault codes of air conditioners give very useful information. As any other kind of equipment, air conditioners can have operational problems. And when it comes to air conditioners, sometimes it is very difficult to understand what went wrong and why an air conditioner doesn’t work properly. But you shouldn’t worry in this situation because Mitsubishi fault codes will help you to deal with it.

When there is a problem with your air conditioner, just check its screen, in particular, check the fault code on the screen. Then you can also find the meaning on the fault code. After this, sometimes you will be able to solve the problem on your own, but there also would be cases when services of a professional will be needed. Anyway, if you understand the fault code, you will know what further course of actions should be.

Mitsubishi Ecodan AC fault codes

FAULT CODEDESCRIPTION
F3Low pressure switch failure - check connection on the board and continuity of switch
F5High pressure switch failure - check connection onto board and continuity of switch
F9Both pressure switch contacts are open at the same time - check connection onto board
and continuity of switch and for a potential board failure
EAMis-wiring fault between FTC and Ecodan - check S1,S2,S3 also check voltages and comms
EBMis-wiring fault between FTC and Ecodan - Check S1,S2,S3 also check voltages and comms
ECUnit cannot finish start up process - generally caused by a comms fault
U1Ecodan high pressure fault - mainly caused by incorrect water flow rates -
check with flow setter
U2Ecodan high compressor discharge temperature - mainly caused by refrigerant
shortage or dirty condenser
U3Ecodan discharge thermistor problem - mainly caused by TH4 discharge thermistor -
open/close circuit
U4Open or close circuit Ecodan thermistors (TH3, TH32, TH33, TH6, TH7, TH8) -
open or close circuit or disconnected from main board
U5Inverter heat sink overheat protection (W50 and W85 models 77°C, HW140 model 95°C -
reduced air flow through Ecodan - faulty fan motor
U6Inverter/Compressor over current - system indicates possible IPM error
U8Ecodan fan motor problem - mainly caused by DC fan motor being disconnected,
connected or obstructed with the power on or possible main board fault
U9Over voltage or under voltage - mainly caused by either CN2 or CN5 loose or disconnected
or decrease of mains power supply
UDOverheat protection TH3 ≥ 70°C or 63HS ≥ 70°C saturation temperature
UFCompressor over current/Compressor lock - occurs within 30 seconds of compressor start
UHAbnormal running current - < 1A or > 40A detected during operation -
check CN5 connections
ULOpen circuit (63L )
UPOver current detected after 30 seconds of operation - do an inverter test to determine
outputs balanced
E0Transmitting Error PAR W21 - check refrigerant address on SW1 of Ecodan
E1Faulty controller
E3Transmitting Error (PAR W21) - check refrigerant address on SW1 of Ecodan
E4Receiving Error (PAR W21) - check refrigerant address of SW1 on Ecodan
E5Receiving Error (PAR W21) - check refrigerant address of SW1 on Ecodan
E6Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
E8Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
E9Indoor/Outdoor communication error - mainly due to Ecodan being powered up before FTC(2)
EFNon-defined error code - noise interference - power down Ecodan for 30 seconds
then switch back on
EDSerial communication fault between Ecodan main board and Ecodan inverter board -
mainly due to loose CN2 or CN5 cable
P1Flow temp sensor fault - TH1 not connected, short or open circuit
P6Over heating at heat exchanger - lack of water flow, air in the system, flow rate
incorrectly set, blockage or pump problem
P8No temp change at plate heat exchanger - problem with flow rate (too high) -
incorrect sizing of system
P9TH5 Fault - TH5 not connected, short or open circuit, FTC not configured for heating only
PEInlet 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)