Multistack issues

[Drew]

Hi all,
Ive got issues with a multistack system that keeps on counting down on its display to load up the modules but once the count down finishes the relevant module doesnt start up? i have seen this on other multistacks , but generally this is because the relevant module has a fault so it skips the faulty one and starts the count down on the next one. In this case, however, there is no fault indicated on the control. So what im seeing on the control is the demand is calling for 100% , the count down counts down,some of the modules start some dont, the activated percentage will get stuck at say 50% and the count down will count down over and over again.. without activating anything and no faults appearing in the fault record?
I have tried to get a detailed manual from dunnair without much luck and sadly the tech support has been dismal.
Any help would be appreciated.

[Drew]

Not much info out there on these things it seems

[Magoo]

Hi Drew,
the only multi stack units I have come across are Temperzone/Bradway water chilers. Could the Dunnair be a re-badged version.

[Drew]

This is a brand called multistack.

[licencetochill]

Hey Drew,
I used to work on a fair few Multistack's when i lived in Wellington, They are hands down, the most unreliable water chiller's iv'e ever seen. But you probably know that already!.
Check to serial cable's linking the relevant module's, ive had these give me issues before.. swap module boards around and prove they are actually good. I'd say ive replaced 30-40 module control boards on these machines.. they are rubbish. I always started working from circuit 1 first, getting that going then move to circuit 2 etc etc..
I may even still have some info lying around, il have a look.

[Drew]

Thanks for that. The lack of a service manual with relevant wiring diagrams makes it difficult to work on. Even the software logic is odd.

[cool_tech]

it sounds like the main processor is faulty. I had the same problem on a M stack. would count down then restart the count. Multistack are in Moorabbin Melbourne. You maybe able to post it to them. The multi stack tech replaced the main proccessor chip. tested on his test bench all ok.

[adam0606]

I have worked on these units, the first thing to check is all your sensors are reading correctly. A faultly sensor can cause this issue.

But more than likely the main PC board in the computer is faulty.

Contact the Adelaide office there is a guy there who is very helpful.