Daikin VRV - REYP10KJY1 - Strange Issues

[troymedhurst]

Hi All

I am looking for some fresh ideas.
We have the above unit that has had issues for a long time with lots of part replacements.
I had the service checker on the system and found a few issues. BS boxes stuck in Heating and a couple of expansion valve head not functioning. With the heads, I manually drove open and re-fitted to stop refrigerant flow.

However the main issue is that with some units in Heating and some in cooling the system runs in Heat/Cool mode. Then I can hear the valve outside change over then the system goes into cooling only. It only goes into Cooling only for a couple of minutes, then reverts back to Heat/cool then starts again.

There are definitely units in heating with thermostat on, so I don't see why it is going into cooling only for a couple of minutes then reverting back???

I was wondering if the system was trying to go to defrost for some reason, but a guy at Daikin discounted that. I am awaiting a call from a VRV specialist at daikin, but was hoping you guys might have some ideas.

Some parts that have been replaced in the last six months.
A1P board
Outdoor stepper motor
Hot gas bypass

Thanks in advance for your replies.

[RusBuka]

Where is LOGs of working machine?

[Asbolute]

I manually drove open and re-fitted to stop refrigerant flow. - This wouldn't stop the refrigerant flow, how did you carry this out?

BS boxes stuck in Heating - Is the solenoid coils wired/installed correctly to relevant BS box?

I wouldn't expect defrost operation in June but the checker data will let you know if system enters defrost. Think you need a Daikin engineer to attend you may have a multitude of issues.