Hello, Martin Pirrie.
We use YCAJ chillers on our CW comm. application, with a part wind starting for the compressors, operating as you said. All I can say is that instead of thermal overload relay, York put the motor's PTCs at work and also, the controller is monitoring the absorbed current...
You could say that is a friendly HMI. You have to know the most common used features for the I/O, and knowing some network programming will help you a lot. The YES also is a powerfull tool if you have access.
The York FM will do the rest for a complete understanding and monitoring of the process.