I recently got a 91 camaro, the fan does not blow any air through the vents at all. There is a "hissing" behind the HVAC unit control, yet I still haven't figured out which line(s) is/are leaking or where. Could this prevent the fan from spinning at all, or would it have to be either the fan resistor or fan itself to cause the fan from not spinning?

 

You need a new Air Conditioning Control Panel Vacuum Control Valve,
1983-1992 with a/c
It is on the rear of the hvac controls.
Possibly one of the vac. hoses connected to it may be broken or leaking also.
There are a few self fix posts on this site if you do a search.
https://www.thirdgen.org/forums/elec...ml#post5278772

This will NOT prevent the fan from working either.
You may have a bad fuse/connection or bad fan motor.

Many Cam/bird sites have them and they look like this
(factory piece is usually white):

 

https://www.thirdgen.org/forums/inte...anent-fix.html

 

thanks guys :-)