I have used them twice now. Prompt, clean, and professional service. I have three units and one is very old. I was told that the unit is old, but not needing replacement yet, unlike the last company that told me it was shot. The advice was to make sure to give service twice a year to ensure longer life.
I recommended them to a friend that owns a considerable commercial portfolio and he said it was the best decision he had made.
All I know is that I don't know about a/c systems and they are very helpful informative and look for a long term relationship, not a one time sale.