My air conditioner works for about 20 minutes then blows hot. If I’m on the highway it works great but stop and go traffic does it in fast. One guy told me I needed a compressor while another said it was a busted shrader valve. At this point we’re not sure who to believe
What kinds of “guys” are these? Are you saying that you had mechanics actually look at it?
What kind of car are we talking about here? Year, make, mileage?
Off hand, I’d say that this sounds mostly like a classic instance of low refrigerant, perhaps coupled with a cooling fan issue.
Don’t assume that just any “auto care” shop can deal with A/C problems beyond just recharging with refrigerant. In fact, most shops don’t have people who are actually well-trained in A/C. Find a locally owned shop that specializes in A/C issues.