Daikin Rmx140jzvmb

[theodore]

HELLO!

I'M HAVING A PROBLEM WITH A DAIKIN SUPER MULTI RMX140JZVMB R407C YEAR 2003.

THERE WAS A PCB BURNOUT AT FIVE OUTDOOR UNITS (OUT OF 100 SAME UNITS INSTALLED AT THE SITE).
THE FAULT CODE WAS U2.
WE CHANGED THE FAULTY PCBs.
FOUR OF THE UNITS ARE WORKING PROPERLY.

BUT AT ONE OF THEM THE SAME PROBLEM OCCURED.
[U2 FAULT & PCB BURNOUT].

CAN ANYONE HELP?

[theodore]

THE POWER SUPPLY IS 232V 49.9Hz. THE BOURNOUT STARTS WHEN THE OUTDOOR UNIT FINISHES THE SEARCH OF THE NUMBER OF INDOOR UNITS ON EACH BRANCH PROVIDER.
THERE ARE TWO RESISTORS OF 39Ω EACH ON THE PCB THAT GET OVERHEATED. THEN THE U2 APPEARS.
THE FOUR PCBs WERE CHANGED THE LAST 10 MONTHS AND THERE WAS NOT A FAULT SINCE THEN.

[Thana]

Are these resistors little green one near the fuses? 2 off? if so you have a neutral problem. i.e. check your local isolators for swithing the neutral or a loose connection. You will always have a problem if you switch the neutrals on Daikens.

[theodore]

Forgot To Tell That The Unit Did Not Run At All After The Pcb Replacement Because Of The "u2" Fault. All Connections Were Double Checked.
I Mean That The Unit Did Not Run A Few Days Before The New Burnout. It Happened When We Tried To Start The Unit With The New Pcb!!!

[SUBCONTRACTOR]

THE POWER SUPPLY IS 232V 49.9Hz. THE BOURNOUT STARTS WHEN THE OUTDOOR UNIT FINISHES THE SEARCH OF THE NUMBER OF INDOOR UNITS ON EACH BRANCH PROVIDER.
THERE ARE TWO RESISTORS OF 39Ω EACH ON THE PCB THAT GET OVERHEATED. THEN THE U2 APPEARS.
THE FOUR PCBs WERE CHANGED THE LAST 10 MONTHS AND THERE WAS NOT A FAULT SINCE THEN.


Just a quick one .Noticed that you come from Greece.Is the system in Greece or UK ???If it is in Greece don't you think 232 V is a bit higher??

[theodore]

the system is in greece.
nominal voltage 230V/400V.
unit's nominals:50Hz 220-240V

[theodore]

the problem is that resistors R250 & R251 get overheated just before the compressor start, after the new pcb installation and two minutes power supply is turned on . Simultaneously the indoor units fans are operating from the same power supply and fuse.

At this unit overheating does not happen during compressor operation!!

I think there is not a power supply problem.

DAIKIN said to check some connectors in the outdoor unit but nothing faulty found.

[sinewave]

If you can obtain one the installation of a Voltage Recorder for a few days would prove your supply integratity (or not)

Any spikes, dips or abnomilies will be recorded and charted for your investigation.

[nike123]

100 units with inverters on one site is lot of EM noise in power supply. Question is, does the electrical instalation is made properly for that particular setup? I think that site electrical instalation need serious examination from specialized electrical engineer in field of EM noise in power supply.
I would start with checking operation of troublesome unit from other (separate) power supply (maybe from generator).