ghfun

All air in the HVAC Electronic Climate control is directed to the floor and windshield outlets in my 96. Initially, the system became very slow to shift from those outlets upon start up to the A/C dash outlets, and then it quit shifting all together.

I have checked the HVAC for trouble codes and there are none for either the Control Head or Vacuum programmer. I have visually inspected the Control head, reseated the wiring harness connection, removed the faceplate, cleaned connections and reinstalled the face place and this did not help. I have checked for vacuum at the black valve on the passenger side of the engine and replaced that valve and this did nothing.

I have always suspected a vacuum problem and still do. My problem is I cannot get the vacuum programmer box out, to ensure the vacuum is actually reaching it and that it is functioning correctly. The vacuum lines connecting to the actuators are so tight as not to give me any slack and the green vacuum line connector seems to be held onto the programmer with a nut, which I cannot get to. So I cannot actually prove the vacuum is getting to the programmer. If I could get it out I could also take it apart for further visual inspection. Can anyone give me a tip on how to get that programmer out or at least how to get the vacuum line connector disconnected so I can get some slack?

When I replaced the black valve out of the engine, it has two vacuum lines connected. I applied suction to both lines and one did not hold a vacuum, the other did hold a tight vacuum. I can't tell which line goes where but if the line that will not hold suction is the one going to the vacuum programmer, I fear this is the problem.

Can anyone help; does anyone have any different ideas?
Mark ghfun@aol.com Thank you to anyone who can help or at least tell me how to get the programmer box out of the car.

ProfMLB

Been there, done that, I gave up on trying to get all the hoses off and to check for leaks. My visual inspection was as yours, everything looked great. So, I just went ahead and did the "big sucker" trouble shooting, I replaced the controller unit and all is well and has been for thousands of miles. I got my controller unit from Jeff Kopp, if you do not know who he is you will find him at 1 800 728-8267. Just call and ask for Jeff, he works for a Chev dealer in Kansas. He sold me the controller for a good price, way under what the local yokels wanted.

ghfun

So what I am understanding is you replaced the vacume programer unit up under the dash above the gas pedal, right? Still how did you get the vacume hoses off without destryoing them? Arent they secured with a nut? This is what I cant get to.

SouthernSon

I just did this about 2 weeks ago. I got the A/C programmer from the Last Detail in Atlanta for $182. To remove the vacuum manifold with all the hoses intact one simply needs to pry the retaining tab on the bolt away from the housing with a very small flat blade screw driver in order to get a good grip with small needle nose pliers. Pull, bend and yank that sucker off of there! It works. Upon reinstallation I found a small nut that fit. But first I slid a short section of rubber tubing over the small bolt and backed it up with the nut. This leaves the nut far enough away from the housing to get a good grip if one needs to do this job again. My air now comes out of each register as should. The new unit may take several seconds to 'reboot' in the computer while you push the different functions. Don't panic, it will work. :smash:

ProfMLB

Hi, no I mean the HVAC controller itself, the computer part with the buttons in the dash. The new unit worked fine and I had the same problem that you had. The helms manual says the part that goes out is usually the computer, when it cannot make its mind up, it sticks to the defrost and floor mode.

ghfun

Hey man, thanks for the info. I thought that retainer was a bolt, now that I know it is pryable I will get back on that sucker. You would think they would put some of that stuff where a normal person could get to it instead of jamming it up in no mans land with no slack. Did you have anything specific that told you to replace the vacuum programmer vs. the in dash control unit? I have someone with same problem who replaced the dash unit and that fixed it for him.

olephart

Another vote for the controller above the gas petal. A friend had the same symptoms recently.

If you want to check before changing, you pull the vacuum line from the engine (at the controller box) and see if you have vacuum - if not, you have a leak toward the engine (usually the plastic "T" fitting under the passenger fuel rail cover).

Then jump the engine vacuum line to each of the lines on the box. When you hook the line up the coresponding valve should function. If they all do, it's the box.

ghfun

HI friend, I tend to agree with you that it is the Vacuum Programmer Box above the gas petal. (Not to discount the other guy who had success replacing the Control Head in the dash). Now that the other guy has told me I can pry the retaining clip off where it holds the vacume lines on to that box, I will check it out specifically. Thanks! Mark