A/C, Heater, Defrost, Everything stopped
 

My air conditioning system all of the sudden has stopped working. Nothing works at all...when i turn the knob to get the car going all i hear is a faint hiss...no air comes out on any setting for heat, ac, or defrost.

Can someone help me? I have no clue how the AC system works on this car.

97 z28 ss

Is the blower working??? Have you checked the fuses??

nope, blower is not working. Are the fuses the ones on the left side of the steering wheel?

when i turn on the blower nob thingy inside the car I hear a hiss. I opened up the dash where the CD player, etc is and behind the knob there is a little thing connected to it. I disconnected it and the hiss is comming from a little hose connected to the back of it. Not sure what the heck is going on, i checked the fuses on the side of the dash and they seem to be fine.. It seems that power is still working but i'm not just getting anything blowing through the vents.

The HVAC control use vacuum to operate the flapper doors that direct the hot and cold air to the correct place. Appears your "hiss" may be a loose vaccum line.

Courtesy of Shoebox:

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

Moving to "General...... F-Body Tech"........

The "hiss" is a really faint hiss, you can bearly hear it unless you get real close. And it's comming from one of the vacum hoses inside the dash. It's making the noise because it's sucking air through one of the tiny holes. Is that normal?

I went under the hood and checked this thing: http://shbox.com/1/vac_check_valve.jpg

I'm not sure what to check for though. The connections seem ok, but the one on the top seemed to come off pretty easily. Is that normal? I was about to attempt to try and test each line like it says on shbox, but I don't understand what it's telling me to do.

"At the check valve, remove the hoses one at a time and apply vacuum to each and see if it holds. The line to the intake manifold will have to be removed at the manifold and plugged back toward the check valve for you to test the line for leaks. If you find a leak on a particular hose, you will have to trace out the cause on that section."

"Apply vacuum and see if it holds"??? What does that mean? Am I supposed remove each hose 1 by one and suck on the hose to see if I can suck air through it or not? Or am I supposed to suck on the actual check valve canister to see if im able to suck air through it or not? I don't get it.

Could someone please explain this in lamens terms step by step because I'm not really understanding what it is telling me to do and how to test it. Sorry.

Also, since I am getting absolutely no air comming through my vents, does it mean the blower is out? Where is it anyway?

Thanks.

You would use a vacuum source, like a Mi-T-Vac hand-held vacuum pump, with a vacuum gauge on it. You pull a vacuum with the hand-held pump, and watch the gauge to see if the vacuum holds.

It says to apply the vacuum "at the check valve" to each of the hoses, one at a time. Not at the "check valve canister". There is a canister in the system, but it isn't a "check valve canister", its hard to understand where you got that idea from.

Lack of air through the vents can either mean the flapper doors are closed (path "D" in the diagram), or the fan is not running. The fan is located in the airbox that starts at the firewall and enters the passenger compartment. It is shown at the bottom right of the diagram I linked from Shoebox's site.

Sorry, all this stuff is new to me and it's a little hard to understand. I don't know what a firewall is. How do i get to the blower if I need to replace it? From inside the dash or under the car? I have a feeling it is most likely the cause of the problem. I don't even hear anything functioning when I turn on the air. It's completely dead.

I guess I have go buy a mityvac to test the lines. Will they have it at autozone? It threw me off because it said you could use your lungs. Thanks for your help injun.

any1?

The firewall is the metal panel that separates the engine compartment from the passenger compartment.