Welcome to the Corvette Forums at the Corvette Action Center!

A/C blowing on floor and windshield FIXED

G

ghfun

Guest
Thank you all who responded. Long story short, I have found that the vacuum hose connection to the vacuum programmer module had apparently worked its way loose enough to allow vacume to escape. I found it fits very poorly to start with. This is probably due to the really weak flimsy push on (over screw threads) metal thing that is suppose to hold the connection tight. When I held the connection really tight all worked like a champ. I am going to find a longer screw for the connector, put a spacer on it so I have room to tighten a real nut for the screw. This should hold it tight and will completely fix the problem. Thanks again to all who responded.

Mark
 
Joined
May 29, 2002
Messages
8,652
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
ghfun said:
Thank you all who responded. Long story short, I have found that the vacuum hose connection to the vacuum programmer module had apparently worked its way loose enough to allow vacume to escape. I found it fits very poorly to start with. This is probably due to the really weak flimsy push on (over screw threads) metal thing that is suppose to hold the connection tight. When I held the connection really tight all worked like a champ. I am going to find a longer screw for the connector, put a spacer on it so I have room to tighten a real nut for the screw. This should hold it tight and will completely fix the problem. Thanks again to all who responded.

Mark


Where is that critter located @ ?
 
G

ghfun

Guest
The critter location

The Vacuum programmer for the HVAC vents is located way up under the dash, near the firewall above the gas pedal.
 
G

ghfun

Guest
Hard to get to

YES, what a pain in the butt. Have to crawl in the drivers floor on your back over that damn hump by the door and jam your head up in there near the gas pedal. There is no room at all and you cant see so you have to have a drop light right there by your head creating all that heat. Then you have one bolt to romobe that holds the programmer on, then you can only move it a little bit because the vacume lines, one in particular the one for the A/C doors has no slack what so ever. After I knew the thing holding the vacume lines on was one of those slip on flimsy things I just dug and dug around to pop it off. When I put it all back on, I got a longer screw (the screw comes up from inside the programmer through the vacuum hose bracket thing) to give me more room to work, cut a rubber spacer then put a hole in it. I stuck the vacuum lines on which is no easy task then slippe the rubber spacer over the screw then it took me 5 minutes to get the damn nut on the screw and another 5 minutes to get it screwed down holding the vacume lines tight. Well guess what the A/C vents blow harder than they ever have because that little piece of s*** fastner had worked loose.
 
Joined
May 29, 2002
Messages
8,652
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
Well mine is definetely having the same problems, so it sounds like I get to have all the same pleasures u had ! :(

Thanks 4 the info . . . :)
 
Joined
May 29, 2002
Messages
8,652
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
Re: The critter location

ghfun said:
The Vacuum programmer for the HVAC vents is located way up under the dash, near the firewall above the gas pedal.

Got to the Vacuum Programmer (VP) and the electrical & vacuum connections seemed tight.

The AC blows to the default, windshield/floor and will not blow to anything else regardless of my selections.

I pulled the VP out and gave it a good inspection. it looked good.

There is gobs of vacuum coming through the black vacuum line.

Any ideas on what to do next?
 
G

ghfun

Guest
Vacume programmer

Are you sure the connections are really tight where the vacuum hoses go to the box? I thought mine were but I had to press and hold that connection very tight to the box and like magic the vents changed. If that is not the problem I would be in the dealership. The connection I had was only held on by a very thin piece of metal that slips over the screw. I replaced it with a real nut and bolt and cranked the connection down. No problem in the last many months, it is still working great.
 
Joined
May 29, 2002
Messages
8,652
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
I remove the vacuum connector out of the VP box and put the vacuum connections together directly and it still didn't work.

I'm not really having fun with this critter!
 
G

ghfun

Guest
vacume problem???

Wow sorry to hear that. At that point I would be taking it to the dealership. I honestly dont know where to go from there. Sorry.
 
Joined
May 29, 2002
Messages
8,652
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
Vacuum Programmer Connections - Fixed !!!

ghfun said:
Are you sure the connections are really tight where the vacuum hoses go to the box? I thought mine were but I had to press and hold that connection very tight to the box and like magic the vents changed. If that is not the problem I would be in the dealership. The connection I had was only held on by a very thin piece of metal that slips over the screw. I replaced it with a real nut and bolt and cranked the connection down. No problem in the last many months, it is still working great.

Mark,

Worked most the evening on it, but I was able to get it working. :upthumbs

Found out you can have it too tight just as well as being too loose. Trimmed the ends off the Vacuum Programmer's male vacuum hoses just a bit and was able to get them tightened down without making them crimp/close off. I replaced the gm bolt with 1 a bit longer and I also used a washer and castle nut to replace that freaking connector some clever gm boy dreamed up.

Thanks for the detailed e-mail and your help !!!

Later,
6 Shooter
 
G

ghfun

Guest
vacuum problem

Wow so you got it fixed. GREAT. I just knew it was the same problem. GREAT NEWS. Yes you can get it too tight. I actually cleaned out the male ends on my unit as well as one of them had some gunk in it. During the cleaning process I did open the holes up some more accomplishing the same thing as you did. Is a castle nut the little flimsy push on thing like I had? I had no nut or not what I call a nut, just this little piece of crap they pushed on. And how long was that suppose to last with that tension? Sounds like a built in obsolescence to me, on a very expensive part that they could easily replace and you would never know it was a half-cent thing. I too replaced the factory screw with a longer one, placed a rubber grommet cut to size over the screw, with a washer then nut tightened down. Been working better than ever.
Man I am so glad you were persistent, I just knew you had the exact same problem.

Mark
 
G

ghfun

Guest
Castle Nut

Nevber mind, I know what that is. Now what do you call the push on thing?
 

larryfs

Well-known member
Joined
Aug 7, 2002
Messages
101
Location
long island
can you guys write this up in a nice tech article :) my 96 appartently has the same problem.

on another forum, the guys said replace the programmer or replace the vaccume check valve under the hood by the pass side valve cover.

I havn't looked at mine yet, and my back doesn't feel up to that pain you describe :) I'll try a flashlight rather than a drop light.

great information though !!!
 
G

ghfun

Guest
This problem seems to be cropping up and including myself there are 3 who simply had to fix/tighten the connection of the vacuum hoses to the vacuum controller by replacing the slip on clip thing. I did replace the engine vacume valve about $5.00 before I found the real problem. I would hate to see someone go to the expense of taking the car to a dealer or replacing the vacuum controler or in dash programmer before exausting checking the vacuum connection.
 
V

vettegirl

Guest
I know this sounds strange, but

it's happened to me twice now...

There is a little hose thingy connected to the PCV valve that disintigrates after a while. Both times this has happened my A/C did the windshield-floor blowing thing. The hose is a dealer item, but just bought another one and it's only $ 6.00. I don't know why this effects my A/C, but it does....another Corvette mystery!

:confused
 
Joined
May 29, 2002
Messages
8,652
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
Mark/ghfun - Thanks for the info, it was/is great.......

larryfs said:
can you guys write this up in a nice tech article my 96 appartently has the same problem.

mailto:ghfun@aol.com

I will go through the steps I went through, although I just knew it was a vacuum problem from the very start. I didn't technically know how the whole system works so I had to do trial end error with a lot of help from people on here and other forums.

Vacuum essentially controls which doors up inside the vent system open or blend to shoot air out which vents in your system. With Electronic Climate control, the Control Head which sits in the dash center console with the control buttons, is simply a little computer that senses outside temp, inside temp, and combines that info with the button you push lets say the auto button, and the air temp you set, to determine which doors to open or close to deliver air to the appropriate vents. It has no vacuum lines attached only electric and data connections.

Over the data lines the control head sends info to the Vacuum Programmer, the one above the gas petal that says open or close the appropriate doors for proper venting. The actual movements of the doors come from vacuum applied through solenoids inside the vacuum programmer as a result of the data sent from the control head.

Vacuum comes from the engine. On the passenger side of the engine near the fuel rail and under the plastic injector cover (it just pops off) is a black valve connected to the engine and containing 2 vacuum lines one of which goes directly to the vacuum programmer.

There are other components but in this case where the airflow is simply stuck blowing in form the heat and defrost vents these are the most important ones. I found out that the default position is heat and defrost when something like this is wrong.

First I would check the trouble codes. To do so you press the fan up and fan down arrow buttons simultaneously and hold till the outside air temp read out LCD, says 00. If no codes pop up then press the fan button, the one between the fan up and down buttons. If still no numbered codes, like 09 or 15 whatever comes up then the on board computer has found no faults in either the Control Head or the Vacuum Programmer. This is most likely good but under some circumstances a code will not show up. If you have a numbered code pop up then you will have to go on line or somewhere and match the code with the symptom and proceed from there. But lets assume you had no trouble codes, just as I did not.

Pop the plastic cover off the top of the engine on the passenger side and you will see that valve. I think there are 2 valves under there but this one has the 2 small vacuum lines going back toward the firewall. I don’t know exactly what that valve does, but it is a valve and serves some function other than splitting the vacuum into 2 other lines. You should have engine vacuum when you pull the lines off. I went ahead and replaced it as it is only about $5.00 and people say they go bad all the time, so get a new one and be ahead of the game when it decides to go out.

So now we have no trouble codes and you are sure the proper vacuum is leaving that valve on the engine and going down that vacuum tube to the controller. Turn over upside down, first grab a flashlight or drop light to take with you. Put your head on the floor up close to the gas pedal. Among all the wiring harnesses, relays and other stuff under there you will see a black box probably about 6 or so inches wide and 1 ½ inch deep. You will also see up in one corner of the box a connector with several colored tubes attached to that box. That connector connects the black vacuum input hose from the engine through the box and out the colored hoses to control the doors. You will quickly see there is almost no slack in those vacuum lines so be patient, as you have to work on the connection up under the dash.

I did not do this initially and I would highly recommend that you do it. You really need a partner but can do it alone. With the engine running, put your fingers on the green vacuum line connector where it connects to this box. Apply pressure to that connector; squeeze it really tight to the box. The objective is to simulate a tighter normal connection between the lines and the box. If the climate control is on auto, you have the temp selected to 60 and it is hot outside the air should shortly (maybe 10 seconds) shift from blowing in your face on the floor to the dash A/C vents. While holding that connection really tight have your partner push some other buttons on the control head and see if the air flow shifts to other vents as indicated on the buttons. If this happens you have a bad or loose vacuum line connection just as I did. IF this procedure does not make the air shift to other vents then you may have another problem.

Lets assume this procedure does simulate fixing the problem. (Even if you get a momentary flash of air from the A/C vents this indicates a connection problem). Now you have to get the box off and out of the car. Ultimately you do not have to take the box out to get a better connection but I found the main black vacuum line to be partially blocked with gunk so it gave me an pportunity to clean it out. Also with the box out, you can take a visual inspection inside to make sure nothing on the circuit boards is
burned up.

Where the vacuum hoses connect to the box you will see a silver screw sticking up through the connector. It has one of those flimsy push on retainers I have already talked about supposedly holding the connection tight. (Someone told me there should be a nut on there but now 3 people I worked with have had the push on retainer). If it is a retainer instead of a nut, you are going to have to dig around with a small screwdriver to get under that retainer and bend it out, and then you can grab it with long nose pliers. However, you need to pop that retainer off. When you do the vacuum lines will fall right off the box. Then you will have slack to disconnect the electrical lines.

Get the box all the way out and pull the pack off, it is cardboard, yes cardboard. You can release the vacuum line board inside by removing two screws. Then you have remove the other board with two other screws. Make a visual inspection to insure nothing on the board is cracked, broken or looks burned.

Next focus on the vacuum connector with the male parts. Remove the screw that holds the assembly to the box and ultimately will hold the connection tight. Replace the screw with a longer one but make sure the screw head is exactly the same size as it fits into molded plastic to keep it from turning as you tighten it up from the outside. Make sure you have a real nut that fits the screw threads. Put your new screw in, tighten the nut holding the vacuum piece to the box, and tape your cardboard back on. I cut a spacer to slip over the screw, which would press tightly on the vacuum connector at the connection and allow me to get the nut on the screw at the tip of the screw. (it makes it easier). Plug the box back into the wire harness then get back on your back, crawl back under the dash. Put the box back almost in it’s installed position and fit the connection to the box. Slip the spacer over the screw tight with the connector base then put the nut on the screw head and tighten with a socket. Doing this upside down is easier said then done but be patient. Tighten the nut pretty sung, start the car and check it out.

NOTE - The system will go through a series of re programming itself before it does anything. Wait a minute or so and if still nothing, turn it off, then back to auto, then press the fan buttons and make sure the temp is set to 60. If all this works you should soon have nice cool air blowing out the ac vents in your face. If it does not try to tighten the nut on the connector a little more, remember you have to have a really tight connection
there.

If this still does not work, take the top off and drive it one last time as a convertible before you drive it into the lake.

Seriously, if all this does not work you probably have a faulty control head or vacuum programmer box and the system just didn’t pick up any trouble codes. From here you’re on your own to figure which box to replace first.

Hope all this helps,
Mark


__________________________________

Torch Red LT4 - Gone but never forgotten! :w


Later . . . . . .
6 Shooter
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom