2002 Jeep Cherokee VENTS BLOW NO AIR

I think it's a vacuum problem. You may have a broken hose or a crack in a canister under there (not sure what the configuration of that system is like--I've only ever had this problem with GMs).

But I've had that cause my ducts not to open on both my parents' '92 Bonneville and my own '98 Astro van.

(I had it fixed at a shop, but I know that was the cause. Sorry I can't be of more help.)