Hi, I am having a difference of opinion with a co-worker and I am wondering if I am right or he is right. His home AC stopped cooling (over time) and he had it cleaned and re-charged. He said the mechanic who charged it said it had lost nearly half its charge. I said if it lost any of its charge, then there had to have been a leak. To me this was common sense and agrees with what I know about car air conditioners. He said that he would choose to agree with his mechanic who said that all it needed was cleaning, charging and regular (once a year) servicing.
Who's right? How else might a home air conditioner lose its charge? If it can lose its charge without any defective parts, how does that happen and what needs to be done to avoid that happening?