Unico Turbo / RC Chiller 620T2 H16

[Grizzly]

Can anyone help please.
I have been to a site today working with colleagues from another region.
Where there are 2 of the above chillers both with 2 systems. Danfoss Turbcor comps (1 on each system.)
Either system is only using 1 system due to the low ambients and load.
The lag chiller ramps up and down and on and off around it's set point. However the lead chiller will cut in at set point plus 2 degrees. Say 9.0c SP. Therefore at 11.0c it starts and pulls the leaving water temp down to 9.0c. ramping down as it approaches SP.
What it will not do is shut down it will trundle along on minimum load with the leaving temp going down to approx 7/8 degrees. Staying at this below set point temp with the comp gently loading slightly and then unloading.
Has anyone any ideas.

Secondly can anyone help with the controller settings or a manual for the above.
I have a code which allows me to check and change a lot of the control parameters.
But I feel there is info I am missing?
The controller is badged up RC, but is based upon a Carel Pco.
Any help or advise would be appreciated.
The main UK agents are Excel Refrigeration I am led to believe, but sadly apparently they choose to not assist in this instance. As it's not their site I do not blame them but can anyone help?
Grizzly

[Tesla]

Hi Grizzly I went to Carel earlier this week and they told me that many of their controllers are rebadged. Perhaps it might be worthwhile calling Carel Technical Support. It does sound like a control issue.

[Magoo]

Hi Grizzly,
I was on a site doing other stuff while the local bloke was commissioning a similar chiller. Most of the set-up was via a lap top, so would imagine that the accessable stuff is limited. You would need the program and access info to get into it. They would have access coded every fix logic program. I think it is called locked in customers and screw them factor.

[Grizzly]

Hi Tesla.
Over here there are a huge variety of chillers that use the Carel pco series controllers.
Virtually all are "bespoke" with individual access codes.
Hence my request on the forum. Hopefully someone can help?
Thanks for the advise tho.
Magoo.. Wise words as usual!
Grizzly

[NoNickName]

I think Carel is of no or little use here. RCgroup software is customised. Carel only produces the hardware.
What they did is just divide the band in two, and assign each half to each of the chillers.
I am quite worried that your current heat load would allow one compressor on one chiller to go below setpoint. It is the plant mistake, not the chiller mistake, so don't touch the microprocessor.