mitsibishi vrf cooling/heating problems

[weidit]

Hi everyone

I have a mitsibishi electric vrf system that is not cooling very well.
The condenser is a size 650
with 16 indoor units.
i have checked the capacity etc and is below the 650
one unit in particular is in a room with a big window and gets sun on it therw out the day. The unit only seems to maintain around 24/25 degrees. With a air off around 22 degrees i would have thought if it was struggling to cool the space the unit would have much lower air off?
looking at the other units and they perform similar. There is ahu feeding conditioned fresh air to the intake (ducted units) which is around 23/24 degress. The ceiling void is the same temp as the actaul office space.

in heating we also only get around 35 degree air off at best.
I suspect it may be sog? so may go and reclaim and re calculate the refrigerant charge.

The pipes to each fan coil are all around the same temp and seem to be getting a temp differance between the two pipes.
Is there something i should look at on the bc controller?
i will also check branch numbers are the same.

any advice appreciated as im booked on a mitsi course in 5 weeks but would like the solve problem before this time..

regards weidit

[Thermatech]

There are a lot of things which can cause poor performance but SOG is a prime suspect
Try this
Only operate one indoor unit in test cool. If you have good off coil temp then put some more indoor units in test cool & see if the performance at the 1st unit starts to drop off. Then put some more units on in test cool. If you gradually see the performance getting worse at the 1st unit then thats a good indicator of system SOG.

I tend to watch the discharge SH as its a good indicator of the refrigerant charge provided everything in the system is working correctly.

[JoeAT50A]

Switch on outdoor units SW4-3 (for *GM and *HM series), run test run mode for all 16 units, wait around 20 to 30 mins. Compressor discharge should be around 85 to 100C, see the pressure level for hi and low side.
And also watch the running current (amps).
If you have maintenance tool, then much easier to adjust and fine tune for the refrigerant amount in the system.
Indoor units' SH (TH23-TH22) should maintain below 5 if you can. Value 2 is ideal ... but not necessary.
If you could able to attach your maintainance tool data, then we could be able to assist you more.