hello fellow problem solvers, i have one, prob a vacumn leak or something, but just as the title says, i have a hissing noise when the a/c is on coming from what seems like the center of the dashboard. the noise will get quiter as i move the dial from cold to hot (blue to red) and will go away when i move the other dial setting to feet or head and feet setting and will also go away when turned off altogether. so it is there when on max, a/c, and windshield. any ideas of where to start looking or anything? also i remember charging the system with freon last summer but now that its been almost a year the air is blowing luke warm maybe a freon leak or something? idk, lol. any help is appreciated.

 

The AC/heater controls are run by engine vacuum. Shoebox has a diagram. Would appear that one of your lines or a vacuum actuator is leaking. Not the hot/cold dial, since that operates a cable.

http://shbox.com/1/hvac_vacuum.jpg