The air intake for the HVAC system is located at the base of the windshield and there's no screen on it. So alot of debris and leaves can easily enter the system and it usually gets trapped in the blower motor fan. The blower motor is located under the dash on the passenger side. Held in place by 3 screws. Awkward to get to but not too bad. Pull it out and I'll bet there's stuff caught in the fan.

I had to do this several times with my Sportage.

1998 Sportage - Gone.
2004 Honda Civic Coupe.
2007 Suzuki Grand Vitara - She got it.