Just an additional info.

I've had a Toshiba a/c for about 4 years now. And throughout these 4 years, I had to have a technician "pump in gas" for at least twice a year. Same problem, the a/c stopped blowing out cold air. Meanwhile, my National a/c in the other room has worked perfectly for 5 years and there isn't one day where this "no gas" problem has ever occurred.

But then, reading from the above posts, it seems like the "no gas" problem is caused by human error so..it all depends on your luck I guess.