When was the last time your cabin air filter was changed?
Is it dirty or clogged with leafs and other debris right now?
When you take the filter out, leave the slot open, and turn your your ac, can you feel it blowing? it should be blowing from the TOP towards the BOTTOM.
If you've ever changed your air filter (especially with an aftermarket Walmart or custom filter), it could have been reinstalled upside down, possibly allowing the filter element to be sucked in to the blower, and clogging your system up.