Ventilation making noises

I have a 2003 Saturn Ion 2 with noisy interior ventilation.
1. When the fan is on (warm or cool air, air conditioner, or defroster), there's a "clicking" sound that comes from the area around the front passenger's feet. It sounds a bit like a cricket, or like something's stuck in the fan (i.e. pine straw), but it's been like that for months, and I just had my air filter changed and there wasn't anything stuck in there. It varies with the speed of the fan; I only hear it on 1st or 2nd speed (although maybe it's just that at higher speeds the sound of the airflow drowns out the sound of the clicking). It's not all the time, just most of the time. It varies in volume. There's no noticeable pattern to the frequency or volume. Sometimes it will briefly stop if you turn the fan all the way up then back down, or off then on again, but it always starts back up again sooner or later.
2. When the air conditioner (or defroster, which includes A/C) is on, it growls! Not always, but usually. The volume of the growl varies. And there's a delay... the growl starts a few seconds after the A/C is turned on, and stops a few seconds after it's turned off. It's kind of like the sound of an A/C compressor kicking on and off. At first I thought it only happened when it rained, but the other day it happened in dry heat.