The heat on my ride only blows out the defroster. I found where the vacuum line for the HVAC starts; it's plugged off. Does anybody know where the hose leads to? I have the automatic HVAC.

The 2000+ HVAC system is electronic. Check out the 2000-2005 section, specifically the common problems thread. There are photos there of the position of the actuators which move the air.

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-Car Guy Carl
"Penelope" - 2003 SLE - 247k Miles
"Sydney" - 2000 Honda S2000 - 98k miles

also there is a re-sync procedure you can try...sometimes the actuators get out of sync.

From GMSI:

Calibration Procedure (without a Scan Tool)
1. Turn OFF the ignition.
2. Remove the battery positive voltage circuit fuse for the Instrument Panel Control Module.

IMPORTANT:
The module memory will not clear if the battery positive voltage circuit fuse is installed in less than 60 seconds.

3. Wait 60 seconds.
4. (re)Install the fuse.

_________________
2003 Pontiac Bonneville SSEI
3.8L V6 SC, 180*T (Drilled),
Custom PCM w/Perf Shift,
SLP Ceramic Coated Headers,
Thrasher Cold Air Intake,
GXP Tails, Interior Door handles, Trim pieces etc.
40th Aniv Grand Prix GTP Wheels (Very Shiny & Very Annoying )