MY 2003 car has clocked 135,000km and I have yet to service the air-cond.
It is still functioning perfectly.
I was advised that I should only service the air-cond when it's not cold.
Air conditioning systems like any mechanical systems need lubricants and
Generally, air conditioning service shops recommend that the system be
serviced once a year.
The service would involve not only checking the compressor and replacing
all the lubricating oil, but also chemically cleaning the evaporator inside
the car of all dirt to bring it back to full efficiency.