1996 ford ranger 2.3 liter

A/C has vacuum leak.blows cold at first then when i accelerate comes out defrost and cool stops until I let off pedal then comes out vents and blows cold. smoke tested under hood no leak. I bought a copy of ford manual vacuum lines and electrical. replaced vacuum accumulation ball with check valve inside. A/C Max is worse than regular A/C. Then I noticed when off Fan and selector off still oozes out cold or hot depending where temp is.
Would it be the A/C unit in cab or a major vacuum leak into cab from accumulation Ball? Replacing ball with chk valve was supposed to be fix, now I don't know where to trouble shoot...