Is there a known or common problem that would cause air to flow from all vents (dash defrost, main and floor vents) no matter what mode you put it in. I've only had the car about 1 month and hadn't really noticed it or thought it was part of the auto mode. Yesterday when it was 100 I went to manual mode and noticed it was still blowing from all three locations.

I'm guessing there's some kind of vacumn line issue somewhere but thought it was worth asking before I started trying to dig around and figure it out. I've got $0 deductible extended warranty so I can let the dealership figure it out but hate to have them tear into it if I can avoid it.

Thanks!

 

There is a vacuum control that designates which outlets the air should route. First step would be to make sure that the vacuum control assembly is getting vacuum. It should be the same as engine vacuum. If not, you need to apply a vacuum pump to the actuator line and see if it retracts.

I have not heard of any common problem, but others may have.

 

do you have any faults? to check,press the "options"button and tap the "fuel" button 4 times.this will put you into diagnostics.it will start with pcm and go to each system from there.
if your car had a battery leak it probably burnt through the vacuum line for hvac.the line is under the battery box/tray

 

Bingo on the last part "battery leak". Will that (vacumn leak) show up in the diagnostics section? Is the section of vacumn line you mention directly under the battery tray area?

As I mentioned, only had the car for about 1 month. Last weekend discovered the battery was leaking and I'm guessing the one before it had too. When I took the battery out there was a ton of acid build up underneath it in that drain type area. I took the battery tray out so I could get at everything a little better. I rinsed it out real good w/ water and then mixed up baking soda with just enough water to be a real thin paste. I used an old paint brush to try to get this paste in and around everything, let it sit a while and thin rinsed it off. Replaced leaking battery and thought I was done. Guess now I get to fix problems the acid leak caused.

 

take off the right front wheel and pull out the inner fender inspection cover[the back of the inner fender well near the door].you will see the pcm,the tac module and the wiring harness and the plastic line for the hvac.make sure the harness and controllers aren't burnt by the acid.
also.if you step on the gas with the car running and air comes out of the defogger duct,most likely the line is burnt through.

 

DPD - Thanks for quick reply, I actually pulled the battery and tray again, may go ahead and pull the fender liner too to get a better look. There is some rust around the pcm but wires look ok but who knows. I found one end of the vacumn line but not the other. Any help with where to look appreciated. The end I found is running back towards the passenger door. When I first found it and touched it about 3 inches of it just crumbled in my hand.

Ugh! I wonder if any of this would be covered under warranty? Not so much worried about the vacumn line but thinking what if wiring, pcm, etc. have problems later on.

 

OK guys we're getting there but slowly, I don't have manuals yet and need some help figuring out where this line goes, can only find one end.

Traced it back to a three way (valve?) just towards the bottom rear of where the access panel covers. The back side of this connector goes to the inside of the car through a rubber boot. On the three way the bottom two fittings are connected and lines appear to be solid and connected. The top line is the one that's crumbled and I can't figure out where it goes to.

Anyone with manuals or previous experience that can tell me where to look for the other orphan end?

 

the other end of the line goes up to the back of the intake.from up top,right side,the line comes up from under the battery tray and to the back of the intake along the firewall

 

Still looking and that's where I was guessing but can't seem to locate. Is it bundled in to one of the wire looms?

Thanks for the quick reponses!

 

I don't think it's the one going back to the back of the intake. I found that one and traced it back through one of the wire loom bundles, it came out and went to that same three way but it went to the bottom port. The middle port goes up into the right front fender (behind hood latch area), goes to a connector and then goes up towards the front of the car in a loom.

Now, where does the top line go to?

Is there a second port on the back on the manifold and I'm just not finding but one of the lines?

 

it goes to the back of the intake.there is a tee back there near the map sensor.it is not easy to get to,but it's back there.

 

dpd, I appreciate the help on this so please don't take this the wrong way but are you sure?

I got my big paw back in there and can feel the connector on the back of the intake. Brake vacumn on drivers side and a vacumn line on passenger side. Vacumn line goes down and into the bigger of the two wire looms that head back to battery area. When it gets back to battery compartment that wire loom splits in a Y, right after the split the vacumn line comes out of the bundle and goes down to the three way valve/connector, bottom connector. I can't find another vacumn line in that bundle or a T in the line once it comes off the back of the intake.

If you or anyone else happens to have the service manual and can double check the for me I would appreciate it. Frustrating when you know it's right there but just can't see it.

 

http://forums.corvetteforum.com/show....php?t=1422586

This has happened many times. Be sure to wash with baking soda. One line goes to A/C, one line goes to air pump solenoid on top of pass wheel well under fender. Routing is from back of intake manifold to a small check valvle just outside pass foot well to air pump solenoid and A/C and on to vacuum tank, also between fender and pass foot well. Try a search for vacuum.

 

I had the same thing when I bought my used c-5. It was a broken vacumm line under the battery. Remove the battery and battery tray, the vacumm line is wrapped inside a plastic protector with some wiring. Just splice in a new section of rubber hose; it's too hard to get to either end.

 

Thanks for the help guys but I'm giving up on this thing for the night.

I have looked high and low for the other end of this one vacumn line with no luck. When I was cleaning it out again with some more baking soda paste I did find about a 4 to 5 inch piece of tubing. It got rinsed out when I ran the hose down in there to rinse things off. When I picked it up it pretty much just crumbled.

Any more hints, pictures, etc would be nice. Someone posted a diagram on Z06 but it didn't help much. I found the one that runs up in the passenger fender for AIR, another that runs under the batter tray, in to a wire loom (the larger one that has some type of small box (relay?) taped to the side of it) and hooks to the back of the intake manifold.

When your under the car at the connection point there's the vacumn tank, a line comes down to a connector/valve with three connections, the top one is the one that's broke and it only has about 6 inches of hose on it.

Amazed that something like this has kicked my behind for most of a day. I did take a second wack at cleaning up the acid though so that's worth something.

Thanks again for the help!

 

I have a 98 and I have the same problem with my vents, I also had a dim display which is fixed myself, I found the problem area but have not yet corrected it. i pulled out my right side fender to ther main vaccum area found that all hoses were connected but there was no vaccum, i took some compressed air and shot some air threw and found there was a leak behind the intake manifold, without vaccum here the doors that control where the air blows out will not work, so i have to remove the intake manifold to fix it, also my oil press sensors shot too which is in the same spot so im gonna try and kill two birds with one stone so if that helps at all....good luck

 

Thanks to postings on this topic, I was able to fix this problem and my baby is working fine (oh, but there were many, many hours chasing false leads until I researched this forum). In my case, I had to remove all the fasteners for the front fender except those in the front so I could pull the rear side away from the car to access the vaccum tank. Then I could disconnect the lines and blow compressed air into them to find the leaks. The top one had two cracks, and I made a cheesy hack to fix it, using some tubing I had on hand to splice the good parts together. It's disappointing design - inappropriate material was used. I'm glad this forum lead me to the solution. Thanks to all who knew what they were talking about.