some food for thought:
an entire aircond system with ALL original denso parts for a 1999 iswara cost 2-2.4k ish.
not including labor/aircond gas etc

a Mitsubishi compressor ONLY for a lancer/inspira cost rm4k+ (SC price) part alone

depending on what needs to be replaced, you can get an idea on why air cond are expensive and why they should be serviced appropriately as it can save you hefty repair bills in the long run as opposed to replacing the entire part.

so if you think an aircond workshop is cheating you, think again.
when in doubt, go for second opinions before proceeding and most importantly go to legitimate workshops authorized dealers (eg: denso authorized dealer) or even SC

while you definitely need to pay more especially on the labor side, chance of them cheating you is a lot less and complaints/claims against them should shit happen/they actually cheated you is a lot more effective than against no name workshops (they don't have much to lose)

compressor runs on oil as well:

similar to car's engine oil.

overtime you'll need to drain/replace, or even top up if there's reduction/loss in oil (eg: lots of usage especially under hot afternoon sun and you always have the air cond at maximum coldness temperatures to induce more compressor load)

typical compressor checking/refill/replace is 40-80k km or 1-2 years whichever comes first, or depending on budget. people tend to neglect this element, and only make noise when it's not working, and usually a LOT of noise because parts are VERY expensive.

not to mention, if the workshops/aircond shops are inexperience (eg: fail to troubleshoot on the first time properly), don't expect the layman to know any better as evident in this very thread.

iswara easy, inspira cooling coil

and yes they do have way better controls instead of a stupid pulley only/magnetic clutch. (lol the entire magnetic clutch melted for my iswara case and the melted liquid splashed and stuck all over around the engine bay)

not sure if that would increase the cost, because damn rm600-800 ori denso compressor compared to 4k is a huge difference for technically the same thing (well, a compressor lol)