We take care of a papermill and we have two units in each generator room, thank God they are chilled water but they are worked to death. Room averages 140* in summer. They have a package unit that has to be cleaned every two weeks in one of the generator rooms that supplies a office area.
Chilled water is nice where you can do it definitely. A lot of areas are too far away from the outside, water, restricted by overhead cranes, etc... Overhead cranes use linterns because of the environment(filthy and 130-160 air temp) Linterns are too pricy for most inplant break room, bathroom, mcc, or control rooms. Some plants are just too spread out for chilled water. Water cooled condensers are awesome but I guess water can't be piped there sometimes or who knows what other excuse. So they shuck in a package unit because it's cheapest. Not really designed for the environment which in my opinion is one of the worst for these. Maximum filth, never split, often washed by dingbats sporting straight chemical pump up sprayers, high air temps, garbage filled squashed improperly sized ductwork... list goes on and on. They continue to amaze me though. Tougher machines than most would believe.
Proper tools can get that coil cleaned on site,, If they have a crane on site I understand. If not cost of crane U can get Proper equipment,, and not the washers at home depot.
Seen worst locations.
Can't use water on it in it's location. What is the proper equipment for cleaning a oil soaked dirt filled split? I think pulling the condenser coil taking it to a wash bay and washing it correctly is the best way.