A/C fan

2001 Ford Ranger 3.0 6 cyl auto (extended cab)…Whether it’s a/c or heat the vent on the passenger side floor sounds like it has a leaf or twig caught in it. It only sounds better when I turn it up to full blast, but it’s SO annoying and I have to turn up the radio to compensate.
Additonally, the cab gets cold/hot just fine, however, the vents do not seem to work exactly like the dial reads, meaning, if I have it on the front vents or the front and floor vents, it still blows like it was on defrost. It seems.
Have a Haynes repair manual but it doesn’t cover this.
HELP!
Am active duty military with 3 kids and a wife all in school so am on a fixed income, for sure. No problem doing the maintenance myself but am trying to be selective on what I NEED to do.
Thank you
Andrew

You have a vacuum problem. That’s why you’re stuck in defrost mode.
Look for rotted vacuum hoses going into the cab, at the firewall area.