I have a 96 LT4 and I have air and I have heat but when I press one of the button on the climate control console the air still only comes out of the vent near the front windshield only. No matter which button I press the air will not come out and blow on me...just out the front vent by the windshield...any ideas? :confused:

vr,
volt

 

It's the climate control programmer, under the dash down in the area of the gas pedal.

 

A/C programer - GM # 16088751 or AC Delco # 15-71773 . $164.43 list $115.10w/s, 8 at lansing

 

Before you spend a LOT of money on an AC controller, look under the passengers side injector cover. Under there is a plastic vacuum check valve that deteriorates over the years. One of the lines connected (or likely not connected anymore) is the vacuum that moves the dampers controlling where the air goes. I have seen 5 or 6 C4's with this problem.

 

whats an A/C programmer? :confused:

 

I think Mr. Dave hit the nail on the head. I had the same problem and the little vacumn valve was the cause. Just buy a new one and try that first, a real cheap fix before I would invest in a major part. :chevy

 

Check under the hood and make sure you haven't bumped any vacuum lines.

 

Air flow out of the defroster duct only is an indication of no vacuum present at the HVAC Programmer or a broken HVAC Programmer.

1. Road test vehicle and check cruise control operation. Does the cruise control work?
No – Check for manifold vacuum on the Vacuum Tank
a. If vacuum is not present, check the hose back to the check valve or check for vacuum from the air check valve. Vacuum from engine but not through check valve - replace valve.
b. If vacuum is present, check for vacuum at the Black hose at the HVAC Programmer Head.

If there is no vacuum at the HVAC Programmer Head, replace the Vacuum Tank.

If there is vacuum at the HVAC Programmer Head, remove vacuum control head from HVAC Programmer. Using a 3 inch piece of vacuum line, jump to each air door actuator vacuum line from the vacuum source (Black line). The results should be as follows:
a. Black to Blue line should fully open the bottom air door.
b. Black to Pink line should fully open the center air door.
c. Black to Tan line should fully open the defogger outlet door
d. Black to Orange line should fully open right side air inlet door
Do the air door actuators all function properly?
Yes – Replace the HVAC Programmer
No – Check for open or restriction in vacuum line to air door actuators or defective air door actuator or binding air door or linkage or replace the HVAC Programmer Control Head.


96's were particularly effected by bad AC programmers. I had vacuum all the way to the HVAC Programmer Control Head and replaced the HVAC Programmer.

Be sure to let us know what you find - and - if the problem is the programmer then you at least know the part number and cost.


[Modified by Bill Burkert, 7:33 AM 8/21/2002]


[Modified by Bill Burkert, 7:34 AM 8/21/2002]


[Modified by Bill Burkert, 7:38 AM 8/21/2002]


[Modified by Bill Burkert, 7:41 AM 8/21/2002]


[Modified by Bill Burkert, 7:43 AM 8/21/2002]


[Modified by Bill Burkert, 7:43 AM 8/21/2002]

 

hmm, could be the check valve im hoping....I jut had my intake manifold and valve cover gaskets replaced. That could easily have been disconnected or damaged im sure. I will keep you guys posted, thanks for all the great advise.
vr,
volt
:cheers:

 

Weriodly enough mine started as a slow openning front door then no opening doors after I replaced the intake manifold gasket but I now have to believe mine was pure coincidence. . . . and now back to you . . .
KTWA

 

hmmmm ....strange you mention that because my intake gaskets and valve cover gaskets were replaced about 4 months ago.... coincidence???