Weird HVAC problem
Thread Starter
Pro
Joined: Feb 2007
Posts: 706
Likes: 0
From: San Carlos, CA
Weird HVAC problem
I did a search and couldn't find a specific answer.
My temp control works great. My heater is hot, my A/C is cold, and the blower does what it is supposed to... but it doesn't come out of the right vents.
Instead of coming out of only the face vents, it will weakly come out of all the vents. Doesn't matter what setting its on, it just kind of comes out of them all.
Now this part is really weird... when I have the system going, and I make sharp turn, say 90 degrees or more, I'll get a big rush of air out of the face vents. But as soon as I'm done with the turn it goes back to how it normally blows.
Is it some kind of vaccuum problem? Are the doors not directing the air to the right vents?
My temp control works great. My heater is hot, my A/C is cold, and the blower does what it is supposed to... but it doesn't come out of the right vents.
Instead of coming out of only the face vents, it will weakly come out of all the vents. Doesn't matter what setting its on, it just kind of comes out of them all.
Now this part is really weird... when I have the system going, and I make sharp turn, say 90 degrees or more, I'll get a big rush of air out of the face vents. But as soon as I'm done with the turn it goes back to how it normally blows.
Is it some kind of vaccuum problem? Are the doors not directing the air to the right vents?
Le Mans Master
Joined: May 2007
Posts: 5,383
Likes: 6
From: hagerstown md
St. Jude Donor '08-'09
The HVAC unit works on vacuum to move the air from place to place. The vacuum comes from the back of the intake, to a coupler under the batter, then inside the cabin to the control unit.
Couple of places to check on this one. First, look under the battery to make sure there is no acid damage to your vacuum lines, and they are all connected properly. Checking the intake vacuum port is a royal PIA. You can't see it, or feel it, as far as I know.
Pull up your DIC codes and see if there are any for the HVAC, and post what you find here. You'll get more help that way.
My bet is you have either a loose vacuum line, or a connection that has come loose.
Good luck!
Couple of places to check on this one. First, look under the battery to make sure there is no acid damage to your vacuum lines, and they are all connected properly. Checking the intake vacuum port is a royal PIA. You can't see it, or feel it, as far as I know.
Pull up your DIC codes and see if there are any for the HVAC, and post what you find here. You'll get more help that way.
My bet is you have either a loose vacuum line, or a connection that has come loose.
Good luck!
Melting Slicks
Joined: Jan 2007
Posts: 2,170
Likes: 6
From: Oilerville Edmonton
St. Jude Donor '08
I had a problem that sounds very similar to what you are having. I also had a screwed up display on the HVAC. I bought a new HVAC head unit (used) and am hoping that will fix the problem. Since my car is being stored for the winter, I have not been able to install my new part. I won't get this done until this spring so I can't help right now.
Good luck.
As I reread my post, I can clearly see I've added nothing and helped you in now way, shape or form :o
Good luck.
As I reread my post, I can clearly see I've added nothing and helped you in now way, shape or form :o
Pro
Joined: Sep 2007
Posts: 548
Likes: 3
From: Northeast NE
I just finished fixing my vacuum problem as mine was behaving exactly like yours....but for the working normal when turning idea. I by no means am an expert, but check for broken vacuum lines under the battery as mentioned above. As far as checking to see if the vacuum line is connected at the back of the intake, some have mentioned you can feel it if you know where to check, but I have another idea, if you ever get access to the vacuum lines under the battery, suck on the one that is supposed to go to the intake and if its connected, you will taste gasoline very clearly. Saved me the hassle of fussing with the intake.
Again check under the battery or take of the access panel behind the RF wheel.
Good luck.
Again check under the battery or take of the access panel behind the RF wheel.
Good luck.
Drifting
Joined: Jun 2003
Posts: 1,510
Likes: 3
From: Life moves pretty fast... if you don't stop and look around once in a while, you could miss it!
CI 6-8-9 Veteran
I had the same problem. Probably a vacuum issue beneath the battery tray. Here is a link with pics of how I repaired the problem. It cost about $1 for the rubber vacuum line to bridge the damaged plastic vacuum (you'll understand from the pics). Zuti
http://forums.corvetteforum.com/showthread.php?t=1458514
Zutihttp://forums.corvetteforum.com/showthread.php?t=1458514
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Racer
Joined: Jun 2004
Posts: 319
Likes: 40
From: Hemet CA
One of our club members had a similar problem in his 98 C5 - vents didn't operate right. He took it to the dealer and a couple of local shops. They all wanted to tear into it for big bucks, replace the vent controls, stuff like that.
My friend had heard of a low freon charge causing a similar problem, but the dealer and shops said no, the charge is fine and wouldn't top it off.
Soooo, being the stubborn type, he finally found someone to give his A/C system a freon charge and the vent systems started working correctly.
If you can get someone to top off your A/C charge, you can at least rule out my friend's solution. Cheaper than a vent system tear down.
Good luck!
My friend had heard of a low freon charge causing a similar problem, but the dealer and shops said no, the charge is fine and wouldn't top it off.
Soooo, being the stubborn type, he finally found someone to give his A/C system a freon charge and the vent systems started working correctly.
If you can get someone to top off your A/C charge, you can at least rule out my friend's solution. Cheaper than a vent system tear down.
Good luck!
Drifting
Joined: Jun 2003
Posts: 1,510
Likes: 3
From: Life moves pretty fast... if you don't stop and look around once in a while, you could miss it!
CI 6-8-9 Veteran
Zuti
