Mitsubishi Heavy Industries fault codes, like Daikin and Mitsubishi Electric fault codes, tell you the air conditioning unit has found a problem. When one appears, record the code, check the manual for your exact model and leave the inside of the unit to an engineer. A code is not a fix on its own. This guide explains how each make shows a fault, what you can safely check yourself and when to call an engineer. Climate Flow Limited installs and services air conditioning across London and surrounding areas.
What does an air conditioning fault code mean?
A fault code is a short signal from the unit's own controls that something is outside its normal limits. Daikin's UK documentation puts it plainly: when a problem happens, an error code appears on the user interface, and it is important to understand the problem and take measures before resetting the code (Daikin UK user reference guide). Clearing a code without knowing why it appeared can hide a fault that keeps coming back.
The same letters, numbers or lamp signals do not mean the same thing from one make to the next, and often not from one model range to the next within a make. Mitsubishi Electric and Mitsubishi Heavy Industries are separate manufacturers, so a code from one should never be read off the other's list. That is why this guide carries no code table: read the meaning of a code from the manual for your exact model.
How do Daikin fault codes show up?
On a Daikin system the fault appears as an error code on the user interface. Daikin's UK operation manuals list the kinds of fault the codes report, among them a signal transmission error between the indoor and outdoor unit, a refrigerant shortage and a fan motor abnormality. They also tell users to consult their dealer about error codes (Daikin UK operation manual).
None of the three is a user fix. Write down the exact code, the model number from the label on the indoor unit and what the system was doing when it stopped.
How do Mitsubishi Electric fault codes show up?
Mitsubishi Electric's split-system service manuals say the Operation Indicator lamp on the indoor unit flashes on and off to show an abnormality, and they tell the engineer to count the flashes before starting service work (Mitsubishi Electric UK split-type service manual). What each flash count means varies by model, and it is set out in that model's own manual.
So count the flashes, and note the model numbers of the indoor and outdoor units. We install and service Mitsubishi Electric systems, including a Mitsubishi Electric split system for a newly refurbished retail unit in Hillingdon.
How do Mitsubishi Heavy Industries fault codes show up?
Mitsubishi Heavy Industries (MHI) is a separate manufacturer from Mitsubishi Electric, so a code list for one does not apply to the other. Treat any list that does not name your model range with care.
The safe course is the same as for the other makes: note exactly what the unit shows, find the model number on the indoor unit's label, and read the owner's manual that came with the system, or pass those details to the engineer. We install and service Mitsubishi Heavy Industries systems, among them the two MHI cassette systems we installed for a restaurant on Orsman Road.
What can you safely check yourself?
The useful jobs for an owner or site manager are recording and reading, not repairing. Before anyone resets the system:
- Write down the code, or count the lamp flashes, exactly as shown.
- Note the model numbers from the labels on the indoor and outdoor units.
- Note which mode the system was in and whether it stopped at start-up or after running for a while.
- Check whether one indoor unit has stopped or the whole system.
- Read the user section of the manual for your model and do only what it describes there.
If your model's manual gives the user a step, such as cleaning the filters, follow its instructions and go no further. Leave the refrigerant pipework and its connections alone.
Which faults need an F-Gas certified engineer?
Refrigerant, pressure and leak faults on equipment containing F gas need a qualified engineer by law, because fixing them means work on the refrigerant circuit. Most split systems and VRF systems (variable refrigerant flow, one outdoor unit serving many indoor units) use an F gas, a fluorinated gas refrigerant. UK guidance says you need an F gas qualification to install, service or maintain refrigeration and air conditioning systems, check them for leaks or recover their gases, and that each engineer must hold their own qualification even when they work for someone else (GOV.UK, qualifications to work with F gas). A refrigerant shortage, a pressure fault or a suspected leak is never a do-it-yourself job.
Leaks are also the equipment owner's concern. Responsibility for stopping F gas leaks is shared between the people who use the equipment and the technicians who install, maintain or dispose of it. Equipment holding F gas above a threshold, set in tonnes of carbon dioxide equivalent, must be leak checked at least once every 12 months (GOV.UK, checking F gas equipment for leaks). Whether your system is covered depends on its refrigerant and how much it holds, which your engineer can work out from the unit's data.
Communication faults between indoor and outdoor units, fan motor faults and anything electrical are also for an engineer. Climate Flow is F-Gas certified, and we install and service systems from a single split to larger VRF installations; we carried out VRF maintenance at Energie Fitness Gym.
When should you call an engineer about Daikin, Mitsubishi Electric or Mitsubishi Heavy Industries fault codes?
Call an engineer when:
- a code comes back after a reset;
- the fault points to refrigerant, pressure, communication between the units or a fan motor;
- water is leaking from an indoor unit;
- the system serves a room you cannot run without cooling, such as a busy kitchen or a server room.
Have the code or flash count, the model numbers and what the unit was doing ready when you call; it gives the engineer a head start on the first visit. You can see everything we cover on our services page.
Whether your unit is showing Daikin fault codes, a Mitsubishi Electric flash count or a Mitsubishi Heavy Industries signal, the first step is the same: record it, check the manual for your model and leave the inside of the unit to an engineer. Climate Flow Limited installs and services air conditioning across London and surrounding areas, with 24/7 emergency callouts.
This guide is general information, not a survey or a quote for your site; every system is different, so an engineer needs to see yours before any work is priced.