How many condenses do you have? Is one a multi head? Does the fault occur when all the heads from the multi head are turned on or only when one is turned off? If one is running, does the other heads coil get cold while off? No? Turn the on and the other off If possible send a pic of the piping coming out of the condenser Answer from Nerfixion on reddit.com
Reddit
reddit.com › r/hvacadvice › uh and a5 error code daikin minisplits
r/hvacadvice on Reddit: UH and A5 error code daikin minisplits
June 24, 2023 -
Bought a new house (~750 sq ft) with daikin minisplits, one downstairs (FTXS18LVJU) and two upstairs (CTXS07LVJU). Was having issues with them randomly shutting off and throwing UH error code and one daikin being 10x colder than others. daikin sent out a contractor (which is bs btw, do they not have dedicated techs that just inspect?) and he said the tubing was wrong and it was a $3000 fix. thought it was fishy, had a 2nd hvac guy come out and he said heat pump (4MXS36RMVJU) had low refrigerant and filled it back up. now all blow fairly cold, but if i turn off one of the daikins, then they still go into error mode UH after ~30 mins. any thoughts?
Top answer 1 of 6
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How many condenses do you have? Is one a multi head? Does the fault occur when all the heads from the multi head are turned on or only when one is turned off? If one is running, does the other heads coil get cold while off? No? Turn the on and the other off If possible send a pic of the piping coming out of the condenser
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What you have is a Daikin Multiport. The problem is likely that the installing contractor mixed up the wiring from the outdoor to the indoor units. Daikin Multiports come with a fix from the factory for this as it’s a common issue. Turn off all indoor units from the remote controllers or thermostats. Remove cover above where the copper line sets leave the outdoor unit by way of two Phillips head screws. You will see a circuit board to the left with several LED lights (4-5 lights). Turn off power to outdoor unit by way of the breaker or the disconnect. Cycle power back on and wait for 5 minutes. Press and release the SW3 button located on the board to the left being very careful not to touch any of the wiring labeled A, B, C, etc. as these wires will have 208-230V active on them. This has initiated the wrong wiring check. If the check has been initiated you will see a flashing pattern of red lights on the board on the left. The test will then run for 10-20 minutes at which time the outdoor unit will shut off. If there were any inconsistencies in the wrong scheme from the outdoor to any or all of the indoor units, then the outdoor unit will automatically correct the wiring internally through the board logic and no physical change will be needed of the wiring scheme. What is basically happening when the wires from A, B, etc. do not correspond correctly to the Port A, Port B, etc. is that the refrigerant goes to an air handler that the blower is not currently running on or is running on low-low, so that the indoor unit begins to freeze up and an A5 error code is given. As you’ve said, the problem doesn’t happen when all indoor units are running as it doesn’t matter at that point that the refrigerant is going to wrong indoor unit as refrigerant is going to all indoor units and all indoor blowers are running. For years this has been the very first thing I do when I come upon a Daikin multiport as I’ve no idea who has been there before me, or if the installer did it correctly or not. It should be noted also that this change is stored in the PCB on the outdoor unit. So in the future if the outdoor unit circuit board is ever replaced or if the entire outdoor unit replaced, the wrong wiring check will need to be done again or else you’re back in the same boat as before.
Daikin
my.daikin.eu › content › dam › DASW › supportavdelningen › Felkoder_SM-TS3errorcode_chart.pdf pdf
Simple Self-Diagnosis by Malfunction Code After Sales Service Division (SM-TS3)
Simple Self-Diagnosis by Malfunction Code · After Sales Service Division
Daikin AC Units split- Errors UH and A5
A5 is a coil over or under temp depending on the mode. UH means another unit on that system has an A5. A C4 is a thermistor failure. You probably had a thermistor failure that reported a bad coil temp, triggering the A5 and UH. It’s a pretty easy replacement. More on reddit.com
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March 19, 2024Daikin error code U0 - 00 on a 4 months old system
Yes so that indicates high suction pipe temperature, which is most likely low refrigerant, but could be other things, like a compressor failing to start or a clogged txv. I would advise touch nothing and call out the installers asap ! More on reddit.com
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September 21, 2024UH and A5 error code daikin minisplits
How many condenses do you have? Is one a multi head? Does the fault occur when all the heads from the multi head are turned on or only when one is turned off? If one is running, does the other heads coil get cold while off? No? Turn the on and the other off If possible send a pic of the piping coming out of the condenser More on reddit.com
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June 24, 2023Daikin Split zeigt Fehlercode A5/UH an, wenn auf Kühlen eingestellt?
Zwei Köpfe, ein Kondensator? Wenn ja, prüf mal, ob der Kopf, der nicht läuft, einen Temperaturunterschied an der Spule hat. Hatte ich schon mal, lag am defekten EEV am zweiten Kopf. Deswegen kam Kältemittel in den inaktiven Kopf und hat den Fehler ausgelöst, weil der ohne Betrieb zufrieren würde. Mit beiden Köpfen an lief’s aber, weil der Ventilator das verhindert hat. More on reddit.com
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CoolAutomation
coolautomation.com › blog › daikin error codes: comprehensive breakdown
Daikin Error Codes (Malfunction Self-Diagnosis)
July 20, 2025 - Following are some of the most common Daikin error codes and their presumed causes. Tired of wasting time with repeated on-site visits, finally diagnosing a problem, and then realizing you lack the necessary parts?
HVAC-Talk
hvac-talk.com › home › forums › ask our pros-owner assistance - no diy advice › aop residential hvac/refrigeration(beenthere zone)
Daikin A5 and UH errors - wiring issue? | HVAC-Talk: Heating, Air & Refrigeration Discussion
July 9, 2024 - Just ran a test 08:10 Lower ground and ground floor units off 08:12 Set ground floor to fan only 08:14 Set ground floor unit to cool to 18C, current room temp is 22C Blows room temp for 15 minutes Stops for 3 minutes Blows room temp for 15 minutes Stops for 3 minutes ... 09:29 UH error on ground floor, A5 error on lower ground ... I notice in the Daikin app that it says "Operation conflict".
JustAnswer
justanswer.com › hvac › vc9z8-daikin-vrv-system-error-uh-code.html
Daikin VRV System Error UH? Expert Troubleshooting Guide
May 19, 2026 - VRV systems often face condenser communication errors and power supply voltage irregularities. When a Daikin VRV system shows UH error, it indicates a system malfunction often linked to condenser issues. Start by resetting the power to clear ...
YouTube
youtube.com › watch
How to fix daikin air conditioner error code uh? - YouTube
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Published March 28, 2022
HVAC-Talk
hvac-talk.com › home › forums › the arpa zone/open membership discussion forums › tech to tech chat - commercial
Daikin vrv 3 code UH | HVAC-Talk: Heating, Air & Refrigeration Discussion
November 17, 2018 - Giving me UH error code. Anyone had this issue before? And maybe a solution on how to fix it. Thank you ... Make sure all the fan coils have power. Something isn't communicating with the CU. Sent from my SM-G965U using Tapatalk ... Definitely lost coms somewhere. If this system hasn't run before the work may not be completed? Maybe check prints or daikin design sheet if available to see how many units you should have and cross reference with units you do have.
JustAnswer
justanswer.com › hvac › mpcbg-installed-zone-daikin-mini-split-system-month.html
Daikin Mini Split A5 & UH Error Fix: Expert Q&A Guide
August 9, 2023 - UH errors indicate outdoor unit overheating—check for blocked condenser coils, dirty filters, or low refrigerant levels. Regularly clean filters every 3 months and verify proper airflow.
Reddit
reddit.com › r/hvacadvice › daikin ac units split- errors uh and a5
r/hvacadvice on Reddit: Daikin AC Units split- Errors UH and A5
March 19, 2024 -
Hey, I have a dual split system with one outdoor condenser unit (2MXS18PMVM) connected to two indoor evaporator units (CTXSO9PMVM5), installed in separate rooms. One of the indoor units started displaying the error code "UH". The other unit is showing an error code "A5". I can't turn on neither of them. Currently there's quite the heatwave where I live, so something might have overheated.
My immediate attention is on the unit showing the "UH" error, as it's where I sleep (the other one is in an empty guest room). If I were to temporarily turn off the unit showing the "A5" error (which I read it might be a problem on the indoor heat exchange of that unit), would it allow the other unit (with the "UH" error, which afaik is a communication/transmission error) to turn on? I'm hoping to at least get the ac on my room running properly until I can get professional help. I'm wondering if anyone has insights into what might be causing these errors or how to fix the one in my room until I'm able to schedule technicians to come look at it
EDIT: After turning on and off all of my apartment circuit breakers, I could the on in my room on, even though it doesn't refrigerate, just ventilate... And the other one is showing that it has the "C4" error
Star-supply
star-supply.com › content › Daikin-Troubleshooting Codes.pdf pdf
Trouble Shooting www.climatecenter.co.uk Daikin Trouble Shooting Guide
Wiring error indoor to outdoor, PCB defect · • · • · • · UH · System malfunction · Unaddressed indoor unit · • · • · UH · System malfunction · Mismatched indoor/outdoor, freeze protect · • · UJ · Communication failure · Defect of accessory device, wiring error ·
Theachub
theachub.com › home › topics › daikin › fault codes › daikin uh error code
Daikin UH Error Code - The AC Hub "Where AC Engineers Unite"
August 3, 2024 - Daikin UH Error Code
ACLogics
aclogics.com › home › hvac error codes › daikin error codes › error code uh
Daikin Error Code UH — Improper connection of transmission wiri | Fix Guide
How to fix Daikin VRV error code UH. Diagnosis: Malfunction of system. Causes: Improper connection of transmission wiring between indoor-outdoor units and outdoor-outdoor units Defective indoor unit PCB Defective outdoor unit PCB.
ACLogics
aclogics.com › home › hvac error codes › daikin error codes
Daikin HVAC Error Codes | Complete List & Fixes
Check operation not executed or transmission error · U4 · Malfunction of transmission between indoor and outdoor unit · U5 · Malfunction of transmission between indoor unit and remote controller · U7 · Malfunction of transmission between outdoor units or outdoor storage unit · UA · Defect of indoor/outdoor power supply · UH ·
RemoveandReplace.com
removeandreplace.com › home › home air conditioning › daikin air conditioner ac error codes
DAIKIN Air Conditioner AC Error Codes
December 22, 2022 - U0 System Shortage of refrigerant or EEV failure U1 System Negative phase, Open phase U2 System Power supply insufficient U3 System Wiring check operation not executed U3 System Mismatch of indoor and outdoor units – Split only U4 System Transmission between indoor units U5 System Transmission to remote controller U6 System Malfunction transmission outdoor to BP unit U7 System Transmission between outdoor units U8 System Transmission between master and slave RC U9 System Transmission error between indoor to outdoor UA System Excessive number of fancoils UC System Address duplication of central controllers UE System Transmission error between indoor and central UF System Refrigeration system not set wiring – piping UF System Terminals 1 and 3 crossed (Split Skyair) UH System System error Refrigeration system set up
Reddit
reddit.com › r/hvacadvice › daikin error code u0 - 00 on a 4 months old system
r/hvacadvice on Reddit: Daikin error code U0 - 00 on a 4 months old system
September 21, 2024 -
Hey all,
Firstly, I've already written the installers. But seeing it's a weekend, I'm unlikely to get anything back until Monday I recon.
Anyways, in short, today, my (relatively) newly installed Daikin HVAC faulted out, with all internal units spewing a U0 - 00 error. I had a google and it looks like the error is refrigerant related. Which makes me worry if its leaking?
I don't know much about HVAC systems, but how risky is it if this is leaking? its R32 gas in there, is it safe to stay in the property for family (and pets) if there is a possible leak on the system?
Top answer 1 of 3
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Yes so that indicates high suction pipe temperature, which is most likely low refrigerant, but could be other things, like a compressor failing to start or a clogged txv. I would advise touch nothing and call out the installers asap !
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I too got the same error after the 1 month of installation, seems like there is a leak in the indoor unit coil and the company had to replace the indoor unit.
TechFaultFix
techfaultfix.com › home › heating & cooling (hvac) › air conditioners › daikin › u0
Daikin Air Conditioner - Error U0 - Refrigerant Shortage / Undercharge Protection
March 27, 2026 - Learn how to fix Daikin error code U0. Daikin indoor unit runs, but cooling is weak or stops; the outdoor unit fan and compressor do not start or stop shortly after starting.. See common causes and step-by-step DIY repair instructions.
Mytour
mytour.vn › home › travel › troubleshooting daikin air conditioner error codes uf and uh
Understanding UF and UH Error Codes on Daikin Air Conditioners | Mytour.vn
November 6, 2024 - When the device reports a UF error, the air conditioner continues to operate normally but fails to emit cold air while displaying a UH error on the screen. Primary causes of Daikin air conditioner experiencing UH error include:
Daikin ONE
daikinone.com › smart_thermostats › oneplus › pros › PhaseTwoErrorCodes.pdf pdf
Climate Talk Fault Code Dealer error code Possible causes Corrective actions
Thermostat internal communication error · ClimateTalk coprocessor was not anle to start. •Conduct a warm start of the thermostat. •Call Daikin support at 1-855-DAIKIN1(option 1) •Replace thermostat if needed · Thermostat · Critical · Internal hardware error ·