the only tool needed to troubleshoot a centrifugal chiller...
1. pocket screwdriver (preferably with a South pole magnet on the end)
much more than that and you are doing it wrong.
if you do what Henpeck suggested and watch the chiller tech that shows up, you can learn how they do it with a pocket screwdriver. if they use more tools than that, you may be over-paying them.
Someday, I hope to be just as brave as Harry Stamper.