1. Release and fully open the glove box. Remove any screws holding the liner in place. This will expose the air conditioning programmer and multi color vacuum hose harness assembly. The vacuum source hose from the engine is black and connects to a violet flexible plastic tube going to the programmer vacuum connector plug.
2. With the engine running, locate the connector on the violet tube where it connects to the black vacuum hose. This connection is about six inches from the programmer. Disconnect the two hoses at this point to verify that there is indeed engine vacuum.
3. If there is not, you have a vacuum source problem. Identify the problem, repair it, and test again for vacuum and for proper air flow to the vents.
If the problem is solved, then you can skip the reset of this write up. If there is vacuum present, you will have to keep searching. In all likelihood the problem is in the male vacuum connector attached to the programmer.
4. Remove the 8mm nut holding the female plug and gently unplug the female manifold vacuum hose connector.
5. Check the male connectors. If they are soft and flexible, this is the problem. Often in addition to being soft one or more of these nipples will break off and remain in the female connector.
[/URL]This shows the clear plastic female connector in place on the installed programmer with the suggested flat washer (circled in red) added for strength.
This shows the interior of the opened programmer exposing the offending hose harness assembly. This assembly will need to be replaced or bypassed with 1/8 inch vacuum hose.
Unfortunately this harness assembly is not available as a service part. However, a similar programmer is used on "C" and "H" cars back to 1985.
Swap out the Harness from an older programmer
6. To proceed with the following repair, first remove the programmer from the vehicle. Trying to fix it while still installed will invariably lead to cracking the case.
[/URL]This clear, plastic female connector may have one or more broken nipples. If a replacement programmer or harness is not used, and a repair is needed, cut the connector off and bypass with 1/8" vacuum hose.
7. If from a used programmer, you can salvage a male connector with firm vacuum studs, open the offending programmer and replace the harness assembly as shown above. Put the cover back on the programmer and reinstall in the vehicle.
8. Before connecting the existing clear plastic female connector, you will need to carefully remove any broken nipples that remain. Now gently push the female connector onto the male connector you replaced in the programmer. Be sure to reinstall the nut using a flat washer. Without the washer the connection may not properly seal.
9. Start the engine and set the controls for cool air. Remember, once the programmer is disconnected electrically it loses its memory. After re-connecting it and requesting air conditioning, it will take a couple of minutes for the system to work as directed. Retest and check again for proper airflow. If it works, you’re done and you can forget the repair below.
[/URL]The culprit: no one is sure why the hoses of this harness assembly become so soft that they crimp and cut off vacuum. But they do, and then chilled air is sent to the wrong vents. This assembly is the same one shown in above, but removed from the programmer.
If you can find an old programmer, swap out the harness. Look for GM #16258434 or AC Delco #15-72278 (fits a Buick). However, there are several programmer part numbers using the same harness. Don’t settle just for this p/n.
Plan B: Repair the existing programmer
If you cannot locate a replacement harness, plan on repairing the existing unit.
1B. Remove the programmer from the vehicle.
2B. Open the programmer and carefully cut the colored plastic tubes at their point of entry into the black connector.
3B. Cut off the clear, female connector. Reconnect each individual hose (color to color) using 1/8-inch vacuum hose.
4B. Complete Step 9 above.
You can save all this effort if you wish by buying a new programmer. But these can cost several hundred dollars.
Considering that this repair only takes about 1 hour, it'* well worth the money saved.