Daikin VRV Indoor Unit EEV Hiccup

[Brian_UK]

I replaced a suspect stepper motor on the indoor coil of a Daikin cassette today, sorry I've forgotten the model number, and I didn't get the results I expected.

When first switched on again I had a -7°C coil temperature showing on the mode 41 readout which was a bit too cold really. I should add that the coil sensor was replaced as well.

Switched the unit off to tighten some screws and when restarted it coil temperature showed as +8°C and didn't change. Air off would drop to about 17.5° and then lift to around 19° with air on at around 24°.

Checked some surrounding units and they were all showing a coil temperature of about +4°C.

Had a quick read of the Daikin Basic VRV Manual and it states that the EEV should be initialised if the motor has been changed. What it doesn't do, however, is tell you how to perform this initialisation.

Any clues or hints anyone please.

[james10]

Shut of the power to the system a few times as the valves need to find their position so to speak when power is turned back on the valve opens so many steps and thinks it's fully open so doing it a few times the valve is fully open and should start working correctly

[sachin230]

For intialisation Polarity to be change,shut off the power of individual unit, fit it properly & again connect polarity as previous

[Crash Pilot]

Carefull you don't overtighten or you can jam the valve. Depending on model make sure the motor is wound in when putting the motor on. This makes it less likely to jam the valve and makes it easier getting the nut on.
Turn the power off and on again and the motor will pulse maximum pulses closed to ensure its starting reference point. If the valve is working o.k make sure you have a liquid lock at the valve or you get the refrigerant flashing off.
This can happening if you have a long pipe run on a fancoil that is operating by itself. The low pressure transducer responds to the low load and drops the capacity steps of the outdoor.You then loose your refrigerant velocity and then don't have true liquid on the high side of the
EEV due to the long pipe length. Once the other FCU are on and have a capacity call the outdoor will ramp and the under performing unit will start working.

Other thing is low refrigerant and low performance across the whole system.
If this is the longest pipe run then this fancoil will be effected the most.

Also are refnets laying flat.

Sorry just bored at home and talking cr*p.
Dont listen me yourve probably got it sorted already.

Cheers

[ktm]

Yea was told by a Diakin rep a few years ago u have to turn the power on and off 5 times to let the valve bed in and find it's correct position. Should b ok after that.

[VRVIII]

I replaced a suspect stepper motor on the indoor coil of a Daikin cassette today, sorry I've forgotten the model number, and I didn't get the results I expected.

When first switched on again I had a -7°C coil temperature showing on the mode 41 readout which was a bit too cold really. I should add that the coil sensor was replaced as well.

Switched the unit off to tighten some screws and when restarted it coil temperature showed as +8°C and didn't change. Air off would drop to about 17.5° and then lift to around 19° with air on at around 24°.

Checked some surrounding units and they were all showing a coil temperature of about +4°C.

Had a quick read of the Daikin Basic VRV Manual and it states that the EEV should be initialised if the motor has been changed. What it doesn't do, however, is tell you how to perform this initialisation.

Any clues or hints anyone please.

Hi Brian,
When power is applied to an indoor unit the PCB will give 2000 pulses to the EEV and note this as being the fully closed position (0 pulses). However a new valve motor is driven fully in and will require more than 2000 pulses to close the valve body.

To initialise/fully close a new valve simply power on the unit wait 30 seconds turn off then turn on again and repeat.

Never loosen the valve motor with unit operating unless you unplug from PCB first, this can result in the motor driving out too far then damage can occur when retightening the motor onto body.

When the motor is removed the valve is fully open allowing liquid to flow into the coil this is probably the reason you had a -7 coil temp when turning the unit back on.

The problem you have could also be due to a PCB fault or BS box valve problem or refrigerant flow restriction.

[Crash Pilot]

Just check that you have liquid up to the valve. BS box could be an issue if heat recovery. Not too many issues. VRVII software issue and VRV III noisy boxes. Possible sub cool circuit problem in BS box in heat recovery but dout doubt it. VRV II had strainer filter issue but usually filter mesh gets stuck in Y7S solinoid valve.In this case whole system suffers from bypassing through Y7s on heat only. Cooling not effected. Few cases mesh found its way to the BS boxes. If you have true liquid line at the eev then the problem is local to the fcu.

Good luck post what you find when you fix it.

[Brian_UK]

OK, thanks one and all.

The system is an old K series cooling only unit, refnets - no BS boxes, and the cassette itself is the third unit in the run with two more after it.

I now have a plan to follow, Monday is "play with local isolator day" I think; I'll let you know how things go.

Thanks again.

[Crash Pilot]

Good luck Brian.I beleive K series were one of the best units. Just reseat motor and dont overtighten.
Sounds like you know what needs to be done to sort this.
If you have other units the same and think it is the pcb then you can always swap pcb with another unit.

Good luck

[Brian_UK]

I like the "Don't overtighten" instruction.

You need to have 12" fingers and 8 elbows to be able to get at the damn thing, spanner tight was not an option.

[Mentallist]

VRV indoor units expansion valve heads should only be hand tightened then nipped up with a spanner. When power is applied to the unit the valve is automatically closed + 50 pulses from the PCb to ensure full closing. If you suspect that valve pin is in the incorrect position (PCB unable to close properly) then you can power down the unit, swap the yellow and blue wires around in the plug. Power up the unit for 5 seconds, power off, then back on for a further 5 seconds. Power down, then swap back the yellow and blue to the correct locations on the plug. Swapping these colours ensure full openeing of the pin, this can be seen if the head is removed from the body. Upon next powering up, once again the indoor pcb will attempt to fully close the valve + 50 pulses. This can be done to all "Open Type" exp valves on all generations of Daikin VRV systems as far back as G series.

Hope you resolve the issue

[Brian_UK]

OK guys, system back up and running again.

Pulled the valve motor and confirmed that it would motor when first powered up. Screwed in pin and refitted before doing a multiple power up/down on it.

Crash Pilot had the answer though.

Thought the valve was noisey and with poor cooling I checked the outdoor unit.

Found the suction pipe flanged connection with a mild covering of oil. Was surprised how loose the flange nuts were; anyway, remade the joint and tested for leaks.

Pressure gauge readings and the system suction temperature gave a system superheat of +/- 25°K. Put a couple of kg back in the system; unit valves operated and the compressor started ramping up again.

Indoor coil temperatures started to improve and cool air came out of the unit again. Result

[Crash Pilot]

Lucky guess I made.

Awesome the amount knowledge people have on his forum. At least I know now were to come if I have a problem.

[Brian_UK]

Lucky guess I made.

Awesome the amount knowledge people have on his forum. At least I know now were to come if I have a problem.

I think the forum is the next best thing to walking away from your problem for a coffee and a think.

Sometimes you can just get too close to what you are doing and forget about what may be the bigger picture.