Hitachi vrf FXNE

[kuti]

Helow every one,I was called to check one hitachi vrf system which was not operating.After checking the compressor winding I started the unit,as soon as I switched the main supply the compressor started to rev.to full speed without the two condenser fans comming on.Since the supply of this machine is some distance away I did not took any pressure readings,I just went running to switch the supply off to avoid any damage.Later the owner told me that another tech.had checked the machine but wanted a second openion as the one before me told him that the compressor is burned.Manual for this one I do not have.Also I noticed that the two condensor fans did not started,I think they start at the same time when the compressor is statred.I checked the motors and found them ok.I visually checked the compressor inverter board for any burned parts but found none.My Question is This,forgetting the condensor fans,if the invertor board is defective the compressor start and if it starts it will go to full ref.
I will make anotyher visit to this unit and spend more time .
Thank you for reading this thread.
Kuti

[Tayters]

Do you mean the compressor started straight away after powering up even when the indoor units weren't calling for cooling/heating or you turned on the power, everything initiallised then the compressor fired up?

If the compressor ran I can't see how it can be burned. It may not pump but then you'd have to check with gauges to confirm.

Andy.

[kuti]

Hi,I had switched the indoor units first from a seperate main switch , than the main switch for the out door unit two levels up .By the time I arrived near the outdoor unit I found the compressor on and went again inside to switch it off again.I asked the client if he has the report from the other tech. but said he told him that the compressor is faulty and gave him an estimated value for comressor replace ment.This unit belong to a Bank.Next week I might have more information as I said before I will spend some time with.I already ave checked the thermisters,If I am not wrong the out door fan speed is controled from the sensor on top of the compesssor,till it is stange why the fans did nt` started as the compressor started.I do not wish to install a new compressor invertor board before solve the problem of the two condensor fans.I had visualy checked for any unpluge connectors ,all was in order.
Thanks a lot for useing your time to help me solve this problem
Regards
kuti

[install monkey]

register on hitatchi website-tried to send u the manual but its 90meg
http://www.hitachiaircon.com/argws/loginAction.do?action=loginForward

[james10]

some of the hitachi vrf's have inverter fan controll boards in them if yours has this then it will be worth checking it out

[Tayters]

In cooling the fans are controlled by the discharge pressure transducer, in heating they look at the suction pressure transducer. Either way they should do something.
As James says they are controlled from a PCB. If you download the service book the details are there to get readings from the sensors and get them displayed on the LED display and maybe the voltage they output depending on the pressure.

I think the sensor you refered to reads compressor or discharge temperature which is used as a safety device but not to control the fan speed.

Hope that helps,

Good Luck,
Andy.

[kuti]

Made another visit and first thing I done was installing a circuitbreaker near the unit in case I need to switch off in a hurry. I continuedunderstanding the unit and checking each item. I found out that the twocondensers fan and the compressor are wired on the inverter board, also foundthat a 2,700micro farad smoothing capacitor was damaged, this I tested with acapacitance meter, also compared it with another one from another unit without problems.Since I found this I did not tried to start .My question is this, the inverterboard damaged the capacitor or the other way. During my years working on CityMulti specially the old units the puhy-200/250ymf-b which had two of thesecapacitors and never found one damaged even when the inverter board was found defective.The Hitachi agent in Malta do not stockthis item and the inverter board have to be ordered, this alone is 450 Euros’ would appreciate ifsomeone give me details of agents for Hitachiin UK or in Italy.

Many Thanks

Kuti

[install monkey]

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