no air coming out AC vents

Can you hear the blower running? If not check the fuses, fan switch and blower wiring. If you can hear the fan motor running then you have a air flow control problem.

If the air comes out of the defroster vents, no matter where you have the selector, the system has lost vacuum. Look for a damaged, broken, or disconnected vacuum hose that goes from the engine compartment through the firewall. Follow it from the firewall to the engine to see where the problem is. Another possibility is that the mode door under the dash, inside the heater box, is broken. These vehicles, along with the Blazers, and S10 Pick Ups were notorious for that. Unless you can do the job yourself, replacing the mode door is not worth it. The entire dash assembly needs to be removed to get to those doors. It's like a 15 hour job at a shop! So if you're going to do it, yourself, I'd recommend replacing the mode door, temperature door, defroster door, and the heater core while you have it appart. So you never have to worry about it again. Jim

The blower motor is not coming on and there is no air blowing from anywhere

And theirs is the problem, a real mechanic is getting hard to find anymore, if the computer says everything is good that’s where they stop. And if it doesn’t have a computer they can’t be bothered.

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