Is it ok to steam-clean aircon?

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An aircon cleaner was posting an advertisement of their services around our block. i'm interested in having our aircon steam-cleaned. we actually just had our aircons cleaned last weekend, but the cleaner told us that they can't clean the compressor well. they need to clean it with water, which they cannot do, because it's not allowed in our apartment building (which is very weird since most aircons here are split-type!). that's why i was considering the steam-cleaning. So anyway... what's your feedback with with steam-cleaning the aircon & the compressor? is it safe? will it not damage the aircon?