My A/C was low about a month and a half ago. I had my mechanic fill it. He could not find any leaks. About a week later it was blowing hot. I pressure checked it and it did not have anything left. I filled it with some that had a leak sealer. It has worked great since. It started to blow hot on Friday I checked the level it was still in the green so I filled it to yellow. Nice and cold until this morning Tuesday now it is cool but not cold. Do not see any leaks.

 

You definately have a leak somewhere that your mechanic missed. Personally i'd take it somewhere else or to a dealer where they specialize in servicing a/c's and have the correct tools. That leak "sealer" is temporary, like a band-aid and it won't solve the problem. I've also heard that they cause more harm than good to the a/c system. Filling it won't help til you get that leak fixed.