Re: Help! A/C doesn't work.
Did you check if the compressor was turning at the times that you didn´t feel cold air coming out?
High humidity is already a factor which acts against a good cooling, because the water particles in the air will condensate on the cold evaporator, transferring its heat to the evaporator. This heat transfer is in fact lost energy and the passing air will be less cooled.
Not sure if your mechanic was talking about a valve, or about the blend doors. Blend door hinges tend to break and then you will not have the disired temperature you want. A repair of these doors requires a complete dash removal, but the same applies for the evaporator itself. Do you have the automatic zone control or the manual one?