I have a 1993 98 olds with the defrost working but no other vents blowing air even though I can here the fan working. nor does the A/C work.
Possibly A/C may need to be recharged, maybe get it diagnosed by a mechanic, before taking action.
Correct and also have them look for a vaccum leak as the vents and blend doors work off a vacuum to open and close them.
My 98 did this and I needed a new climate control panel, after it was installed everything back to normal!
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