Just got in from starting my car up and let it run for a bit. It has been in storage since October and I'm home from school, so I've decided to see how she starts up.

I started it up, and turned the floor vents on and it started making a loud knocking sound near the lower dash area, it does this on ANY vent setting except the recirculate. Under the hood, you can hear a bit of a sucking sound, I noticed the hose from the valve cover to my turbo is loose, but shouldn't be the cause....The sucking sound under the motor was more of a pulsating sound.
I also noticed the sound was louder near the power steering resivor, popped open the cover and the pulsating sound turned constant, put the cover back on and it went back to pulsing.

Car idles fine and boost gauge reads a -20 at idle which is normal for the car. I know the HVAC is regulated by vacuum on the jbody, so could it be a vacuum leak somewhere?
Any ideas?

Ok never mind the pulsating vacuum sound now. Figured that out.

Now the major annoyance and problem is the knocking in the heater vent area. It is under the lower dash where the fan and resistor is. The sound is there even with the fan off, but like I said on any setting but the recirculation it does the sound...