2010 Civic LX A/C stops blowing cold air after 15 minutes
 

My 2010 Civic just started doing this... it stops blowing cold air after about 15 minutes of driving, but only on very hot days (temps over 85 degrees). If I keep driving and wait, after awhile, the A/C kicks back on, but it takes quite awhile for this. I have already taken it to a mechanic that I trust, and he replaced some valves that he said may have been causing a leak and recharged my a/c with refrigerant. It was still happening, so I took it back and he tried cleaning the valves again but said they were still pressurized, so he isn't sure how a leak could be coming from that area. He did say that there was a small loss of refrigerant since it was recharged last. I am hoping for some suggestions to give him if this keeps happening (I think it will). Again, this only happens on really hot days, which is extra frustrating because he can't replicate the problem when I finally get the car to him (not a hot day). Also, when the a/c kicks back on after it dies, there is a odd smell, kind of like feet. Maybe this helps. Thanks for any suggestions.