Can anyone tell me what exactly controls the switching of the a/c vents? I have a '91 RS Camaro, and it just started blowing out of the defroster only, and will not blow out of the regular vents. The blower motor works fine, and the temperature works too. It just won't blow out of the vents.

 

You have a vacuum leak somewhere

 

Take the front part of your console apart and check out the vac. hoses on the back of the (max a/c vent heat bilevel, etc) slider. There is a round sort of vacuum switch there with lots of lines running to it. That is where I find the vac leak most often. Sometimes just unplugging it and plugging it back in works, sometimes it takes some grease or something to help it seal. The defrost vents are sort of a "default" for the system. It takes vacuum to reroute the air to the lower vents. Let us know how it goes. Good luck

 

The tab on the back of the control (connected to the visable slider) that selects vacuum ports broke on mine leaving it stuck blowing air out by my feet. It is replaceable, just not as a new part. Best odds are going & getting a diff one from a junkyard donor (,,if what I said is what's wrong).

------------------

• My Firebird

The mind is like a parachute, it only works when its open

 

Well, I opened up the dash controls and unpluged the vacuum lines. I inspected them all thoroughly and they all seem to be in good shape. My next question is where do those lines get their vacuum supply from? I know it comes from the motor, but where do those lines run to? Where on the engine supplies the a/c controls with vacuum?

 

That is an excellent question. I've never had to go any farther than the controls in the console to find the leak. Just an idea, but if you can't follow the lines to wherever they go in the engine compartment, maybe you can blow some air or something through the unplugged ends and have somebody listen and see if they can hear it leaking out anywhere.

 

I think it's the brown one that supplies the vacuum. I know it sounds stupid, but hey I did it, make sure the car's running before tryin to change vents. Make sure there's vacuum on the brown line, if not, check for kinks and leaks all the way back. If there is vacuum then your problem lies in the selector area (round black piece that looks like a maze) make sure it's sealing. check in tech/general engine for posts on the HVAC system

 

gotta get it fixed quickly? thought you were selling it

------------------
91 Z28
Best Time Slip:
60' - 2.098
1/8 - 9.137 , MPH - 76.21
1/4 - 14.213, MPH - 97.55

Mods: SLP Exhaust, umm...nothing else..sorry

Stereo: Alpine 855, Infinity Kappas all around, Infinity 150x2 amp (POS), Infinity Perfect 10 in hatch.

Webpage coming soon.

 

LOL...I'm trying to get it fixed. This started happening after I posted it for sale!!

 

purple is the vacuum supply line. blue is for heat/def. red is for upper mode. brown is for lower mode. orange is for recirc.

If you remove that rubbery manifold that connects to that switch and put some vaseline in each of those tubes (using something like a q-tip), your problem will most likely go away. If not, next easiest thing to do is do separate, or disect, that manifold into individual tubes and reattach each one as a single tube. you don't want to replace that whole "harness", unless you want to tear your dash all apart...

KAM