they myth depends on how to look after the air-con. just like your engine, it needs periodical service and maintenance. so compressor oil and air-con flushing and freon maintenance should be kept maintain all the time. if your compressor is running low on lubricant, it will breakdown early. if there is no frean gas due to leakage, then the compressor will have trouble working properly. and if there is blockage on the airway. then the compressor will work so hard that it will get faulty soon. for me, leaving on to the max is a need, cause i prefer not to sweat while the air con is working either.

if not mistaken, the air-con works accordingly to the timing of the engine. when the compressor is working, the timing of the vehicle will increase. correct me if i'm wrong