97 Lesabre AC

[mmclean27]

Got a 97 Lesabre Limited and iv'e got the AC finally back running however now only the top vents and down by the lower vents work. Even if I select to blow out of the middle vents there is no change. Im just glad that my AC is finally back in working order however I don't want to increase the cracking in my windshield by blowing cold air over it. I have a local junkyard with 5 or so cars to take parts from. Any Ideas? Thanks in advance.

[imidazol97]

Originally Posted by mmclean27

Got a 97 Lesabre Limited and iv'e got the AC finally back running however now only the top vents and down by the lower vents work. Even if I select to blow out of the middle vents there is no change. Im just glad that my AC is finally back in working order however I don't want to increase the cracking in my windshield by blowing cold air over it. I have a local junkyard with 5 or so cars to take parts from. Any Ideas? Thanks in advance.

Take off the hush panel above passenger's legs. Take off glovebox door. Find the violet vacuum line to the black line coming from under the hood. Disconnect. See if you're getting vacuum there when the motor is running and if it's strong.

If not follow vacuum line from upper intake manifold next to the brake booster hose. Check rubber connectors for cracks and leaking. Follow black plastic line to connector at T near the accumulator. Check connectors. Follow line to front of car under fender to the reservoir. Check connector and bottle for cracks. See if you've got vacuum there by pulling off line after running. Should get a good whoosh as air goes back inside.

If you do have good vacuum inside the car,

http://www.imcool.com/articles/airco...acuum_line.php

For bypassing the soft plastic connector on corner of the programmer box.

Use a small rubber vacuum tubing in pieces about 1.5 inches. You can buy by foot at auto parts stores.

[mmclean27]

Im not sure my original post was clear enough. The AC blows and it blows cold. The only thing is that the area in which the cold air blows does not change. On the Climate Control panel you can select to blow either to the windshield, the floor or the middle panel. When I turn on the blower...hot or cold... the airflow will not change from blowing both to the windshield and to the floor at the same time. At all times the windshield and floor are getting all of the airflow. When I use the AC I like to have the airflow come from the middle vents but its not able to flow through once I have set the Climate Control unit to the middle. Airflow does change speeds however from low to high without issue. Only issue is the direction in which it flows.

[mmclean27]

So I guess what my question would be is....what controls where the airflow is directed?

[imidazol97]

Originally Posted by mmclean27

So I guess what my question would be is....what controls where the airflow is directed?

The vacuum that I talked about goes to vacuum motors. The vacuum pulls a diaphgram which moves a lever that opens or closes a door inside the HVAC box. There are 3 of them. One moves a door to close off the defroster ducts and make air come out the front of the dash. One opens the flow to the floor and the same one has another vacuum line that makes it open halfway for floor and windshield setting. The third moves the door to allow inside air to be recirculated back through the blower motor; it's above the brake pedal.

The programmer box on the corner of the HVAC box controls the vacuum flow.

If you have NO vacuum, you'll have defroster with some air bleeding on the floor. That means a problem getting vacuum from under the hood, most likely.

If you have some vacuum and collapsed nipples inside the connector on the corner of the programmer box, when you turn off the motor and leave the key ON, you can change controls on the dash buttons and hear various vacuum motors move some for 3 or 4 changes before the vacuum runs out.

[mmclean27]

Got it fixed. Thanks for all the help and of course you were correct with your diagnosis. I really had no idea how the system worked. I had what was described in the link as "soft nipples". Once I saw that I just attached the vacuum lines directly. About a 20 minute fix as the longest part was just getting the AC programmer in and out. All in all I learned a lot and now I know my way around this area of the vehicle pretty well.