Where the heck do I start?
Start with the branch circuit or circuits that are feeding the chiller skid, and go from there. There's at least one main branch circuit for the compressors, possibly another for crankcase heaters, one or several for the loop pump(s). Then, you have whatever the control system is for the pumps to diagram out, possibly electric 3way valves, thermostats, etc. There's really no generic way to answer this one, but maybe a little more info as to what use the chiller will be put to would help (comfort cooling, process cooling, etc.)