You have a vacuum leak. Usually find the hard thin vacuum line that runs from L/H top of the engine acroos the front and over to th eR/H fender broken. But it could be from any part of the vacuum system.
You may need to have your AC charged
If the fan is working but not blowing air out of top vents, It is a vacuum hose. You need to take engine cover off to get to hose.
You could have a vacuum leak, a bad controller, a bad air door or an electrical problem.......
The climate control is not operating for the passenger side. Check to insure the physical controls work, and the diverter vents are opening to let the cool air to the passenger side.
If the air vents of the Chevy trailblazer 2004 are not blowing air, have the fuel pump checked.
maybe the a/c needs to be recharged with freon
The most common cause of an air conditioner not blowing air is a plugged filter. Be sure your filter is clean.
If central air conditioner turns on but is not blowing through the vents, check the filter. If it is dirty, change it. Change the thermostat into cool, this will defrost the air conditioner.
If your Safari GMC air is blowing in low only, you should check for loose vacuum lines. It could also be that the blower is about to go out and will need to be replaced soon.
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you may just be low on freon
No power, no air! Simple