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Buick LeSabre Heating / Cooling



  • Seeing how I am not the most intelligent when it comes to car fixing lingo, are you saying this could be my issue and fixing the broken tube may fix my issue and make my defroster work?
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,046
    > make my defroster work?


    Your defroster works when no vacuum is applied to the diaphragm under the dash. The broken tube is probably lowering your vacuum coming to the inside of the car. So the defroster should be working by default.

    Actually there is a T in the vacuum lines under the hood up by the dryer for the AC. It's bundled in with electric wires in a ribbed covering. The T has one line to the motor, one to the inside of the car, and one to the tank behind the front wheel. So the leak by the front wheel should be lowering your vacuum.

    Your engine might run a little better with the vacuum leak fixed.
  • OK, I need to do the steps you outlined earlier.

    "The tube you're looking for is blue striped. Take off the plastic hush panel under the dash on the driver side (I think it needs to be removed to see) so you can see the vacuum motors above the accelerator area. The one you're interested in has a rotation mode with an axis parallel to the firewall and horizontal.

    With the car off push the diaphragm in from the back. There should be movement same as when vacuum pulls on it and the door should move inside the HVAC box to close off the defrost and make the air come out the dash.

    Then With the car running and the controls set for the dash vents , put your finger behind the diaphragm motor and push the diaphragm in. The diaphragm should already be pulled in. Then pull off the blue striped tube--they are held on by a safety loop so remove carefully. See if the diaphragm goes open. "
  • 98 Just stopped blowing air. System in on, full blast at 90 degrees. What could it be? Is there a fuse for this or a hose?
  • I have read through the posts here and have checked a few things as I could (it's in the 30s here and hard to work outside the vehicle) but am not sure exactly what to do or where to go.

    First off, I have a 1998 Buick Lesabre Limited that was recently purchased. It has a digital temperature control as well as passenger side controls. The passenger side controls seem to be working, the heat and air work as well.

    However, I am unable to use my front defrost setting. Also, the driver's side vents do not work very well. This is a definite problem being that I am unable to keep my car from fogging up while driving except by not using heat/air and rolling down the windows (remember it's winter, here).

    The floor vent works fine. When on mid/floor the driver's side works slightly and the passenger side works full force. When on mid only the floor is still running, the passenger side is full force and the driver's side isn't working. When on windshield, nothing comes out except passenger side mid.

    I pulled the passenger panel out as well as the glove box. It appears that the vacuum assembly was removed at one point and it is no longer connected to the control box and is instead hoses are hooked to it in what looks like a bypass. I can supply a picture if needed. I have no way of knowing if this was done correctly.

    As it was getting late I was unable to check to see if I am getting vacuum inside the car but will do that tomorrow.

    I also looked under the driver side to see if I could find the diaphragm but was unable to discern where it is located.

    Any help would be greatly appreciated.

    Thank you.

  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,046
    edited December 2011
    >However, I am unable to use my front defrost setting. Also, the driver's side vents do not work very well. This is a definite problem being that I am unable to keep my car from fogging up while driving except by not using heat/air and rolling down the windows (remember it's winter, here).

    With the dash control unit OFF, there should be no vacuum applied and the air flow should be to the defroster on both sides. If the air doors change flow from floor to defrost and dash, you probably have vacuum. You may not have FULL vacuum due to a leaking line. Check the plastic line at the back of the manifold next to the giant tube for the power brake booster. They deteriorate where they are hottest next to the engine.

    Check the line and the plastic bottom under the driver side front fender behind the headlights and in front of the tire.

    There is a T at the line in the bundle of electric wires next to the accumulator. You can take off the cover over the Relay Center and get to them. Ahead of the T. on the intake manifold side, should be a one-way valve to prevent air going from the intake to the high vacuum stored on the passenger side when the throttle is wide open and vacuum drops. I recall one person saying that valve was bad.

    You can check the vacuum getting inside the car to the HVAC unit by following the violet tube from the programmer to the couple it has with the black tube that comes through the firewall--just pull hard to get them apart.

    If you are having mosture problems, it could be 1) from the recirculation vacuum motor being stuck ON or 2) there could be coolant seeping in the heater core (do you get a coolant smell) or there could be air conditioning condensed water in the bottom of the HVAC box that didn't drain out. How long has it been since you used the AC?

    I am not Cleo (the pschic from info commercial fame) but I see some upside down time for you checking on the actuators, electric and vacuum, under your dash.

    The vacuum actuator all the way to the left above the brake pedal is the recirculation actuator. With the car running, check to see if you can push it forward from the back of the diaphragm. That is open--the vacuum sucks the rubber diaphragm forward. The movement on that one is slow because there is a plug in the line to slow down the changes. When you turn on recirculate, that one should move forward and you'll hear the air being sucked in through that air intake above the toes.

    The blue stripe line goes to the defroster actuator diaphragm. It shuts when vacuum is applied. When it shuts, air is forced to come out the dash--and the actuator at the bottom for the floor vents should be relaxed--off.

    When you put it on mid and floor, the bottom actuator moves halfway and some air is allowed to come out the floor and some is forced up to the dash vents. Or if it's on windshield/floor, the air goes to the defroster.

    When you have it on floor, the other hose on the bottom one gets vacuum and the air is forced out the floor with a small bleed amount to the windhield to clear it of fog.

    It is possible that whoever rewired the tubes at the programmer didn't get them hooked up right. The inner color tubing inside the programmer is different in a couple of cases from the color of the output at the coupler which it sounds like they took out of the line due to it's softening and sucking closed.

    Most common is the electric actuator on top of the HVAC box above the programmer not working because it's slipping inside due to a cracked plastic gear. You can unsnap the metal rod and manually move the arm on the heater box and change the temperature demand. I don't recall if the top is the passenger or the driver.

    The other actuator close to the programmer box is from the box to the arm inside the lower part of the HVAC box. That controls the other temp for passenger or driver. It might be unsnapped.

    The only reason for the air to behave different on passenger or driver flow is the blend doors connected to those two rods from the electric actuators. By unsnapping them, you can manually move both with the motor running and see which one affects heat for passenger and for driver. It's possible the air door is broken inside the HVAC box.

    Do some experimenting and see what's working. I can give some pictures and sketches if they might help.
  • atsbc03atsbc03 Posts: 3
    edited December 2011
    I will start working on the steps as you stated and will let you know what I find. I am attaching pictures of the bypass that was done.



    In response to your questions/comments:

    "check plastic at back of manifold" - looks to be ok. starting to dry rot and will have to be replaced eventually but doesn't seem to be the problem

    "plastic bottom under driver's side fender behind headlight" - can't really get to that (if I am looking in the correct place)

    "check inside vacuum" - i am getting vacuum pressure on the inside.

    I have used my a/c recently and it works and I do not get a coolant smell.

    Most of the items under the dash around the HVAC and programmer seems to have been replaced recently (very clean, new looking tape, etc.)

    I will update the remainder as I finish checking them.">
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,046
    The pictures are far too small to be helpful. Can you post larger versions in the Photobucket?

    The vacuum storage is behind the headlights viewed from under the car. Lie on the ground and look up in front of the housing around the front tire on the right side!

    Is the dry rot letting a small amount of air seep through weakening the vacuum?

    Are you in an area where it is warm enough to require the AC occasionally? Is that why water may be in the evaporator and causing moisture on the cold windhield.

    Or is the recirulate valve on. If I drive with recirculate on in cool weather, my breath and other moisture will fog the windshields and side windows on both leSabres.

    Or you may have moisture under the carpet from water leaks in the car
    Or you may have water in the trunk from a leak. That puts enough moisture into the car to be a problem.

    But my test would be the diaphragm on the recirculate valve and be sure it's in the outside air position. I'd remove the vacuum tube and plug it and see if it's being actuated by miswiring of the tubes.

    In fact, I'd probably disconnect the vacuum to the inside and plug the tube and the whole system should be in defrost. That would test if the tubing was connected wrong or the dash control or programmer is doing something wrong. No vacuum means defrost should be the settings the vacuum actuators. Air should come out the defrost.
  • 2002 Buick Lesabre:
    When the heater is on it blows hot air through all vents on drivers side and cold air on passengers side. This car comes equipped with a passenger temperature control on the door. I've tried everything, even the air conditioning and found the same problem with warm air still coming out the drivers side and cool air on the passengers side. Could sure use some advice on how to rectify this problem.
  • I will try and make the pictures larger.



    I went ahead and disconnected the system at the lines. As soon as I did the defrost started working. I am going to go ahead and work this weekend on taking out the programmer and seeing why it was not connected properly. I believe the half-[non-permissible content removed] bypass is the biggest problem. Once I remove the programmer I will either replace the problem valves or bypass it correctly. Any tips/ideas on how to get out the programmer or how to correctly bypass it? Once I do that I will see how it works and let you know the outcome.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,046
    edited December 2011
    the programmer is held on to the corner of the HVAC box by two screws.

    There is a large multiple connector to remove. IIRC it is hard to pull even after unsnapping the safety.

    There is a small two or three lead connector from the programmer that clips onto the electric actuator on top of the HVAC box..

    The color of vacuum tube inside the programmer does NOT match the color of the output when it gets outside the square plastic connector on the corner of the programmer.

    If some of yours still go straight through write those down to record which two go together. I am not able to tell from my old programmer because I don't have the inner and outer plastic connector.

    You might be best off if you have aquarium tubing or small vacuum tube from an auto store that is a tight fit over the plastic lines to just completelly cut out the plastic connector.

    The top of the programmer box snaps on with three different kinds of snaps but it does come off making it easy to get to the inside lines after you cut them off at the plastic connector.

    here's picture of the programmer with the top off.

  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,046
    I found the tube colors inside the programmer and the same tube outside the programmer on the way to the vacuum motor:

    Inside, pink; outside, pink.
    Inside, yellow; outside, green.
    Inside, red; outside, white.
    Inside, orange; outside, orange.
    Inside, blue; outside, blue.
  • gleno1gleno1 Posts: 3
    Hello suttonjeff,
    I am having the exact same problem on my 2002 buick lesabre, did you find a solution? I'm in AZ. and won't survive. Thanks. gleno1
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,046
    edited January 2012
    If both of you have the passenger door control, then this is probably the blend door actuator for the driver side. Take off the panel under the dash carefully.

    Lying on the floor, seat, or somehow, look up at the side of the HVAC box in the middle. There is an actuator about the size of the palm of your hand. It has white parts that move, the rotor and the actuator. With the key ON and the heater ON, change the temperature setting: you should see the rotor move to change the blend door. The blend door forces air through the heater or lets it bypass the heater and does all settings inbetween.

    Here's a diagram of the box with the actuators marked.

    The dual control is a CJ2 AC unit. The single control without digital readout is C67. That's the code on the trunk tag on top of the spare tire cover under the trunk carpet.

    This is the part, I think, for the 2002:

    It's the AC Delco listing here at
    ACDELCO Part # 1572972 {#89018375}
    You can find a 5% discount number places on the web to put in the rockauto order page where it asks how you found us.
  • I purchased an 02 Buick Lesabre Custom a few months ago and everything was working fine up until a few weeks ago. At first whenever I turned the air or heat on the fan would kick on right away and start blowing. When I first started having problems I would turn the air on and the fan wouldn't kick on until I reached about 55 mph. But a few days ago the fan stopped coming on at all, but I can still feel cold air/ heat coming out depending on what I have it set on. Any suggestions would be helpful. Thank you.
  • The heater on my 02 LeSabre Limited will blow one day, and not blow the next. I checked all the fuses, before it decided to start working again for a day. Could the problem be anything but the wiring? Also, the Chilton manual for this car absolutely sucks, because it encompasses such a large span of model years. I also have no idea how to disarm the airbag if I need to take apart the dash. It's January in Montana, so I kind of need my heat!
  • gleno1gleno1 Posts: 3
    I could'nt believe that adding more freon would take care of cold air conditioning blowing out of passenger side but only room temp air blowing on driver's side! imidazol97 I checked the blend door actuator for the driver side like you suggested and it was working fine. Thanks for your responces. gleno1.
  • gleno1gleno1 Posts: 3
    I could'nt believe that adding more freon would take care of cold air conditioning blowing out of passenger side but only room temp air blowing on driver's side! imidazol97 I checked the blend door actuator for the driver side like you suggested and it was working fine. Thanks for your responces. gleno1.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,046
    Tap on the bottom of the HVAC case where the blower is with the toe of your shoe with the key ON and the blower set to work. Probably it's the worn brushes. It might be the connector a few inches away from the blower motor. You can reach your foot across the tunnel and tap up gently.That vibration is usually enough to make contact, for a while. Then the motor may give out completely.

    The blower motor is just above the passenger's left toe. There is no plastic shield under it so it's visible with a flashlight. It has either 3 screws or 5/6 screws to remove it, depending on whether it's the early version or 2nd version.
  • jumped in car the other night and no heat. The lights are all light on the panel. checked all fuses that i could find for the heater (the 30 amp one on the fuse block under the hood, and it looks good. Tried sliding the lever for all speeds and nothing, tried the a/c for the heck of it and nothing. No air movement. this fall I replaced the high speed blower relay to fix that issue, so i went to the next step and just fininshed putting in a new blower --still nothing. Am I missing a fuse location somewhere. The fuse block under the drivers side doesn't indicate anything for the heater. But like i said all the buttons lite up when pushed.??????
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