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1999 Lesabre Limited A/C air flow issue

Roadrunner69

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1999 Buick Lesabre
I have a '99 Lesabre Limited with Auto Climate Control. It is hot here. When I turn the AUTO on, the air blows from the defrost and maybe the floor vents, with little to no air flow out the dash vents (even if set to "mid"). After the A/C runs for about 10 minutes the air will start coming out the dash vents. If I stop and shut off the engine, the whole process starts over when I restart.
I saw a thread that described pushing the OFF, AUTO, and RECIRC buttons at the same time to get fault codes, but it doesn't seem to work on mine, unless I am doing something wrong. The display just keeps showing the ambient temp.
Any ideas? Thanks.
 

imidazol97

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You have no or weak vacuum coming into the programmer box OR you have a problem with the plastic coupler that connects the
various vacuum lines from inside the controller box to the lines going to the 3 vacuum diaphragm motors that control the airflow.
I think I remember those numbers right...
Your system is a vacuum controlled system. Starting with 2000 the controls were all electronic. On yours the air flow doors to the passenger side for temp control and to the driver side for temp control are handled by metal rods from the programmer box.

Check at the vacuum storage bottle behind the headlight in front of the right front wheel. There's a connector there that comes off. If you have someone start the car after you have disconnected it, you should be able to use your thumb over the end to determine there is vacuum. If you have vacuum at the line,, the bottle may have a crack and be leaking air in. If you have vacuum there, plug the end of the line with a golf tee or pencil and see if the system inside the car behaves better. Also check the lines inside the engine compartment that feed vacuum from the intake manifold to the right side through a one-way valve and to a T connector. From the T, one line goes inside the car and the other goes forward to the storage bottle.

If the one-way valve weren't working you'd not know it unless you're going up a long hill where the engine vacuum drops low for a period of time.

The T valve may be under a thin cover of some kind, if I recall correctly. Check any parts of that system that are rubber rather than nylon type plastic because it ages and cracks and leaks, due to heat along with the age.

Then you're off to the inside of the car where the black line from the T goes into the dash and a connector before the pink link (IIRC) to the programmer.

Search for repair discussions on this forum for the leSabre from 1995 to 1999. There have been several about troubleshooting and then bypassing the soft plastic connector. Note that the colors of the lines from the programmer to the plastic connector are not necessarily the same as the color after the line is on the other side of the plastic connector. I connected them together with small gas line rubber pieces from an OReilly store. They had pieces in their junk box from cutting lengths of various lines for folks.e
 

Roadrunner69

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Thanks. I'll check it. I drove it earlier today and by the time I had been driving for 10 minutes or so, the dash vents were starting to put out some air, with air still coming out defrost vents also. It will eventually come out the dash vents, but it just takes a long time.
 

imidazol97

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Here are more of the original troubleshooting and work articles with pictures. This is the one that was the original and I could not remember the webpage and only found it by accident in a post I'd made on here long ago.

How To Correct Mis-directed Cool Airflow in 1996 GM C & H Cars

97 lesabre with mid air problems

I hope these posts help you trouble shoot the problem.

Remember there are lots of articles about electric actuators. Those are on 2000 and later leSabre and Bonnevilles. And Park avenues had vacuum up till 2005 IIRC.

You can go to the diaphragm that operates the mode door between defrost and other, blend door(s), the double diaphragm with two vacuum lines into it that operates halfway and fully sucked in, and the recirculation air diaphragm and push in from the back side on the diaphragm inside to see that each vacuum door moves okay. You can also go there to see if the diaphragm is moving when it should with the dash control in various settings.

But you either don't have good enough vacuum into the interior or you have the famous plastic coupling problem with the little rubber nipples inside that soften and suck over the opening blocking vacuum flow.
Since you get air flow out the dash, that indicates your diaphragm may be okay and not leaking air through the flexible parts.
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imidazol97

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Yes. Take out the glove box with about 7 screws along bottom edge.
Take off the plastic sound panel under the dash on right side.
But do testing to see if vacuum is coming in from under the hood first when engine is running.

The programmer box has a rod that just snaps onto a plastic piece. Mark the length where it's attached.
It looks like it is a screw but it just has ridges on the rod like threads.

The small actuator on top has a couple of screws holding it to the top of the programmer IIRC.
One of those controls the blend door for the driver side and one for the passenger side.

Turn the HVAC off before you start working. After finishing turn the key On and wait for programmer to
find itself. I forget the pattern but you're supposed to turn the temp all teh way down and wait for the
programmer to run everything that way and then turn it all the way up and let the programmer go to the
other end of the temp range.
 

Roadrunner69

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Success. It was the connector. I bypassed it with vacuum hoses and everything works like it should.
The hardest thing was getting the screws back in for the glove box hinge.
Thanks for your help!
 

imidazol97

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A couple of related posts for troubleshooting that got sidetracked and didn't get posted into this topic:

The plastic vacuum line from the programmer to the defroster/Vents diaphragm is BLUE according to my FSM. The 3 vacuum motors are on the driver side of the HVAC box above the accelerator. Try pushing on the one with the blue vacuum line going to it with the car running and the blower on. See if the air comes out the dash vent: push on the back side with your finger through a large opening into the plastic diaphragm.

Since you've got a vacuum tester, with the dash controls on AC, see what vacuum you're getting at the line there. Since you have vacuum into the programmer, and if the air flow goes to the ash vents when you push from behind, and if you have no vacuum at the line when you should, either your programmer unit is bad or the squishy plastic vacuum connector on the lines at the corner of the programmer is sucking shut. You said some vacuum eventually gets to the diaphragm after driving and you get some air flow, so that helps indicate the programmer might be switching on the vacuum to the squishy plastic connector for the lines to the dash vent vacuum motor.

While you're under the dash on the driver side and the engine is running, you can press different controls on the dash and watch and feel the various vacuum motors pull to operate their doors inside the box. The logic is that the defrost/dash motor direct air away from windwhield down to the box. If the floor motor is relaxed, it is closed and the air comes out the dash. If it's under vacuum the air comes out the floor vents. And it's the motor with a vacuum line in the center which stops it halfway so it lets air come out the dash and the floor both.

The other vacuum motor switched to inside air instead of outside air for the recirculate mode. For most people with problems with the dash motor, the other lines seemed to operate okay.

Good luck.

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imidazol97

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Did you have to remove the programmer box from the car or were you able to get to the small tubes to reconnect them without the plastic connector with programmer in the car?
 

Roadrunner69

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I didn't try to cut the tubes from the connector with the programmer box in the car. I just pulled the programmer out and took it apart.
Once you do it, the job would be real easy, but when doing it for the first time it took a while because I didn't know where everything was and didn't want to break anything that I couldn't replace.
 

G-264927

I have a '99 Lesabre Limited with Auto Climate Control. It is hot here. When I turn the AUTO on, the air blows from the defrost and maybe the floor vents, with little to no air flow out the dash vents (even if set to "mid"). After the A/C runs for about 10 minutes the air will start coming out the dash vents. If I stop and shut off the engine, the whole process starts over when I restart.
I saw a thread that described pushing the OFF, AUTO, and RECIRC buttons at the same time to get fault codes, but it doesn't seem to work on mine, unless I am doing something wrong. The display just keeps showing the ambient temp.
Any ideas? Thanks.
I found how to fix this issue. Drop the glove box. It’s 2 little rubber pieces holding it up bend them outwards and the glove box will drop. Then you are at the problem. To the right hand side there’s a black box with different color lines running to it. Wiggle that box a little and I bet it pops on
 

G-59178

Great. Glad you figured it out.
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