UF / UP / U6 fault code

As the largest independant Mitsubishi Electric service and repair company in Adelaide South Australia we see a lot of Mitsi units. A common fault we see on Mitsubishi Electric ducted systems is the UF, UP or U6 error code. This fault code commonly represents a fault within the Outdoor Power PCB, Compressor electrical circuit or Compressor bearings. Of these 3 similar errors codes, the most common to see is the U6, UP or UF. This will be displayed on your wall controller after the unit tries to run 10 times in a row without success.

Mitsubishi Electric define UF / U6 / UP faults as follows

UF - Compressor overcurrent interruption (when compressor locked). Abnormal if overcurrent of DC bus or compressor is detected within 30 seconds after compressor starts operating.
U6 - Power module abnormal. Check abnormality by driving power module in case overcurrent is detected. (UF or UP error condition).
UP - Compressor overcurrent interruption. Abnormal if overcurrent DC bus or compressor is detected after compressor starts operating for 30 seconds.

Common issues that can cause U6 / UF / UP faults

Failure or the Power PCB in outdoor unit
Electrical failure or fusion of Compressor
Seized bearings in the Compressor
Disconnected/broken wiring to the compressor
Closed service valves at outdoor unit
Low voltage at outdoor unit

Tests to determine faulty components

Testing your Mitsubishi Electric air conditioner to determine the cause of a U6, UF or UP fault is relatively straight forward if you know what to look for. Below is the main checks to determine what component has caused this fault. These test are not DIY and will require a Mitsubishi Electric specialist to test correctly.

Disclaimer - Electricity is dangerous and can kill you. The following information is for educational purposes only. Tests must be performed by an authorised service provider or Mitsubishi Electric specialist. Do not try this to perform these test without the proper expertise and qualifications.

Check for correct voltage at the outdoor unit, 240v or 415v
- If power feed is incorrect, contact a licensed electrician or SA Power Networks to rectify power supply to unit/property
Check both outdoor service valves are fully open
- If valves are shut, open valves
Check for visual damage to the Outdoor Power PCB. This could include lizard or rodent damage
- If damage is found replace Power PCB then further test unit operation
Check for visual damage to the wiring between the Power PCB and the compressor. This could include lizard or rodent damage
- If damage is found, replace damaged cable
Check for correct DC voltage to the compressor is equal and correct
- If DC voltage is incorrect, replace Power PCB
Check for equal voltage output from the Power PCB diodes using an inverter checker
- If inverter checker LED’s are unequal, replace Power PCB
If the voltage and diodes have tested correctly and no visual damage is found, it is likely the compressor bearings have seized
- The compressor will need to be replaced and the unit further tested

Costs involved to repair your Mitsubishi Electric air conditioning system

It is important to ensure the correct tests are completed to determine what part requires replacement. It’s an expensive exercise to replace a compressor when only a damaged wire or PCB is to blame. The cost to replace the Power PCB can range from $800.00 - $1,300 depending on the model of your Mitsubishi Electric unit. Compressor replacement cost can vary from $2,500 - $4,000 depending on the model of your Mitsubishi Electric unit. The amount of refrigerant, outdoor unit location, access and labour involved to replace the compressor will also contribute to higher costs. Ensuring the correct parts are diagnosed is vital to make certain you do not waste money on unnecessary parts.

In a nutshell

UF/U6/UF faults can be caused by similar problems
Correctly determining the faulty part can save you $1,000’s
Using a Mitsubishi Electric specialist will ensure the problem is correctly diagnosed and repaired

Need help?

T&K Airpower have been working to keep Adelaide homes comfortable for the last 20 years. We specialise in Temperzone, Hitachi and Mitsubishi Electric air conditioning units and know how they tick. Do you have a U6, UF or UP fault displayed on your Mitsubishi Electric air conditioning unit? Give us a call and we will be more than happy to help.

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Testimonials

After contacting your office enquiring about a warranty on our air conditioners remote control yesterday morning 26/3/2018 at approx 10.30 am, we were advised of an 1800 number and the response was amazing. We recieved an sms yesterday afternoon advising us that a new remote was on its way and we recieved it in this mornings post 27/3/2018. WE RATE THIS COMPANY A 5 STAR RATING IN REGARDS TO CUSTOMER SERVICE. THANK YOU TO ALL CONCERNED.

Mr. Saler
Adelaide, South Australia

Good morning
Wow was the only word I could think of to describe the customer service that your company provides.
Over the last 4 years I have unsuccessfully attempted to get a fault corrected in the Temperzone RC Ducted AC unit that is installed at our residence. Today I was pointed in the direction of T & K Airpower (by Temperzone HO in Sydney) as being the service company to approach. From the initial phone call to your Company, I was truly impressed with how my situation was handled. Millie was helpful, knowledgeable and empathetic to the situation and, I feel, went out of her way to ensure that I received a good outcome. She was a delight to deal with and should be commended.

The fact that the service call was able to be scheduled for the same day, despite the location being on the Southern Fleurieu at Victor Harbor, was a bonus. And your service men, Brett and Sam arrived at the scheduled time! They were well presented, professional and were able to resolve the problem within a very short time. Another added bonus was that they carried the spare parts necessary to fix the problem. Within a hour of their arrival, we had a perfectly operating AC system again.
Brett also took the time to answer all our questions and took us through the best operating procedure for the system.

Margaret & Graham
McCracken, SA

"As for the work done, fantastic! Very pleased with the installation. I went and had a look on the weekend and spoke to the tenants. The job was done very neatly and the tenants praised the professionalism of your staff. It was a lot different to what they said about the other AC company."

Barry
Mawson Lakes, SA

"I had 2 quotes to get my apparent unfix-able air conditioner replaced not very good timing with xmas around the corner I stumbled across TK Airpower and it ended being a simple fix saving me thousand of dollars. Lesson learnt here make sure you use qualified and experienced service repair agents."

Brendan
Lenswood, SA

"Awesome service from a really excellent and friendly team."

Kemeri
Banksia Park, SA

"I called to say we were absolutely thrilled with Marty's work he fixed our air conditioner and its working perfectly... It's an older unit, a Bradway and we didn't want to spend anymore money he tried a few things as the unit was only working 75% and whatever was done as a part of the service worked a treat we couldn't be happier.... Please thank him and pass on our feed back we really want him to know what a great job he's done and how very happy we are!!!"

The Hounslow's
Netherby, SA

To the team at Airpower.

As a small business owner myself, I think it's important to receive feedback from customers both good & bad in order to see how we are perceived in the market place. From this feedback we can make changes to improve or it can confirm we are on the right track. Unfortunately customers are quick to complain but slow, if at all to give praise and thanks for a job well done. Based on my experience in the past weeks of getting my air conditioner repaired I would like to say how impressed I am with the way your company conducted its self. The girls in admin were always very cheerful & friendly when communicating with me & at all times kept me informed as to how the job was progressing. Marty who carried out the on site work conducted himself in a very professional manner arriving on time, fit & ready for work. He was friendly & informative during his time on site & carried out his work with speed & accuracy. Congratulations all on a job well done. I would be more than happy to recommend your company to anyone seeking assistance in the service & repair of air conditioning units.

Kind regards,
Bruce.

Bruce, Blewitt Springs
Blewitt Springs

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Megan Sage
SA

"Great all round professionals .They supplied and installed my split a/c at a very reasonable price. Highly recommend."

Geoff
Tea Tree Gully, SA

We have just had our air conditioner serviced and some parts replaced by Sean and Abbey. Their level of service was outstanding. They were efficient, friendly, professional and cleaned up after themselves! THANKS.

Mr Ramsay
Adelaide, SA