I do not know if they use Freon, but I think they do, and there are more green house friendly Freons, for houses, cars, refrigerators, chillers, dehumidifiers are all they same type of systems, and use a compressor to compress the "freon/refrigerant", then as it it is "blown" over an orifice it expands and causes a cooling effect in the evaporator section, where the fan blows the cool air into a system, then the freon goes back to the compressor to be compressed to repeat the cycle.
If you need to add Freon, it leaks. You better off finding the leak, and put a stop to that than to keep refilling up.
As to the Freon, it depends on how old is the chiller. The older chiller use Ozone-unfriendly Freon, while the newer types are more green. No pun intended BTW.
