I went to used my air conditioner the other day an I can not get any air coming from the upper air vents. I switch over mode to bottom and I did get a little air. I went on "Vette Doctors" web site and I found a thread to remove the number "27" fuse to reset the doors. I try that but still no air. The site also suggested to check the vacuum lines under the battery. I removed the battery but did not see any lines apart.

Thanks,
Gary

 

Got any codes? When you check codes, go ahead and reset the HVAC if it has codes or not. Pull the panel on the bottom of the passenger dash and check to see if you have any vacuum in any of the vacuum lines there, with the engine running.

 

Have you replaced the intake manifold lately? The source of the vacuum for moving the ventilation doors is from a small hose at the back of the intake manifold. It's hard to reconnect, and many people extend it an inch or two while they've got the manifold off.

 

My air didn't change for YEARS until I saw the post about battery acid eating the hard plastic lines. Search on here and you will find DETAILED instructions how to fix this. First thing is remove battery and tray (4 bolts holding it in) and FLUSH LIBERALLY with a couple of gallons of boric acid solution EVERYWHERE UNDER THE BATTERY. THEN look for the black plastic line going thru the firewall in the MIDDLE of the electrical wire cable and ending in a purple rubber connector that goes the the vacuum switching manifold. The other end SHOULD go down and under the passenger fender to a check valve. New valve from GM is over $6 but about $3.50 in the "HELP" section of Advance Auto. The OTHER line goes from the check valve to the middle of the cable going toward the ENGINE. I looked for 2 days before I found the end after unraveling the electrical tape around the cable. Don't just cut off a few inches or you will be doing it again an a week or so (GUESS HOW I KNOW THIS). Go back to good plastic and find rubber vacuum hose (I used almost all of a 6 foot package I also bought at Advance using a piece of the old plastic line as a sample to get a good tight fit). You will be AMAZED after you complete this repair. If you have the original Delco battery replace it. They tend to leak out of the positive post after a few years. BIGHANK

 

Thanks for all the help! I have try some of the suggestions that you have given me. I did change the intake manifold in the fall before the car was out for the season but I think I have used the air before that and it worked fine. My last resort is removing the intake manifold and checking that line. Does anyone know of a way to check that before removing the intake again?

Gary

 

Pull the panel on the bottom of the passenger dash and check to see if you have any vacuum in any of the vacuum lines there, with the engine running.

 

I will do that now.

Thanks,
Gary

 

The vacuum line is the one coming THRU the firewall and is black plastic ending in a PURPLE connector. If no vacuum there with the engine running then check for frosted lines under the battery as described above. DON'T PULL THE MANIFOLD if the lines are rotted under the battery. BIGHANK

 

Thank for all the help, the problem was the vacuum line behind the intake manifold. It came off. I reattached and added some tape to keep it in place.

Gary