New air con don't need chemical condenser, only need chemical
blower in 2 years. 
An air-con unit that is more than 10 to 15 years old, won't last
much longer. Have you thought about your compressor spoiling on you
tomorrow? You would have wasted money chemical cleaning your
compressor, it will cost at least $600 to $700 to replace your
compressor, with the extra $230 you paid, might as well get a new
air-con.
Not necessary. My air con is now working very well after yesterday
cleaning.
every 5 years than I do chemical cleaning which cost $230. Next
time I will just try to find a cheaper company lor.
If I install new air con, say it cost 3k. With 3k and I clean
the air con every 5 years, 3k can do chemical cleaning for more
than 50 years.
I might not even be able to live up to 50 years you know
