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Buick LeSabre Heating / Cooling



  • I had the same problem with my 98 buick. They have a weakness in the air intake plenum. It is what sits on top of your eng, that the intake air come into and distributes it to intake ports, It is made of a composite- fiber -sort of like fiber- glass. Near the entrance, driver's side of the eng , there is an egr. valve which is ported into this. that port(which is cast into the plenum) is surrounded with a flow of coolant, The wall between the egr port and the coolant deteriorates with heat and time . Mine failed around the same mileage as your son's. The result is that at first there is seepage into the intake, then as it get worse it will leak enough so that it will drain down into whichever cylinder that the intake valve is open on, when you last shut off the engine, and as a result bind as you try to crank it because it will try to compress the coolant that had built up in the cylinder. In mine I caught it in time so that it didn't end up with a blown head gasket. Everything below the plenum was fine. I just had to replace it . It came with all the necessary gaskets. It is a good idea to drain you Coolant before changing it so that it will not leak into the oil pan as you are working, however it is important to give it fresh oil and filter at the same time. Hope this helps. PS you can examine the old plenum after you remove it. It will probable look charred around that port. It is a hole vertical up into the air intake plenum at the front (driver's side) about 3/4 inch diameter. If you have the means you can cap the other openings for coolant in the removed plenum and pressurize it. check around that port for leakage.
  • I have a 97 Buick Lesabre with Dual Climate control. When I first start the car and turn the heat on it waits to get to a certain temperature and then starts the blower. That is working normal. I only get heat out of the drivers side. The passengers side blows cold. If I turn the temperature down to 60 and back up the 70 then it will start blowing warm air and seems to function normally. I pulled the glove box out to see if there was a loose linkage but everything looks good. What do I look at next?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    The electric actuator on top may have a cracked gear inside. This allows slippage and the programmer (box on the corner of the heater, the computer) loses it's reference. Moving to cold and then back up lets the actuator reset a reference and move again.

    You can watch the link for movement while you move the heater control temp on passenger side up and down (with key ON). Actuator has wire connecting to programmer. It has two little screws on top that are barely accessible.

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    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • dm26dm26 Posts: 1
    I have an 00 Lesabre with no heat. It has the manual slide system, not dual control. The thermostat is ok, blower works fine and directs to the correct vents when setting is changed. The A\C works. I tried another dash control unit, same issue. Is there a valve or vent door that is not opening? If so is it electrical or vacuum? Is there a way to test?
  • dewc3dewc3 Posts: 35
    I have a 97 lasabre that when you have the heat on the floor setting, it will blow out hot air on drivers side floor vents, but will blow out cool to cold air for the passenger side floor vents, what could be the problem making it do this? Any help would be appreciated :cry: The same goes when you have the mid level vents on as well
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    You have two electrical actuators--if you have digital readout with a passenger control AC system.

    One controls the driver's side temp
    One controls the passenger side temp

    Take off the hush panel above the passenger's legs. On the bottom of the heater box is a white lever that comes out of programmer box. It snaps onto a small rod that has ridges on it like screw threads. it may be unsnapped. Or the motor for the plastic link is not working.

    The actuator on top of the heater box close to the top of the programmer also actuates a vane inside the heater through a small rod. Check to see if one of these work when you operate the temp control for driver (main) and then check to see if the other work move when the passenger control is varied. Be sure to have the key ON when trying this.

    The actuators may have cracked a gear inside the box. The actuator for the lower one is inside the programmer box which has all the vacuum tubes coming out of it. I assume it requires replacing the programmer.

    I forget which one, top or bottom, controls which temp.

    You may want to take off the glovebox lid by removing 6 screws along the bottom. I think that makes it a lot easier to see. And I think the lower lever is kind of protected by a snap on shield.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    There are electric motors that move the vanes inside the heater box.

    For most if I understand poster's comments, the axles are white and you can see them move in response to different commands from the controls with the key ON. Take off the hush panels under the dash to see the controls. You may need to look on driver and passenger side both.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • My 2002 Buick Lesabre heater is blowing cold air only. Would this just be the thermostat?
  • My 2002 Buick Lesabre makes a sloshing sound usually when the car first gets going. Some fluid is "sloshing around but I'm not sure what is causing this. At first I thought it might be the gas tank but it doesn't matter if tank is full or not. It sounds like it is coming from the engine or dashboard area.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    Your engine is old enough it might be a thermostat opening too soon and the engine running cool. If you are engine aware, open the hood after the car's been running on a normal short drive of at least 10 minutes, an feel the upper radiator hose. It should be very warm to touch if the thermostat is staying closed and letting engine water come out when the water is 195 deg.

    If it's really warm, and you can tell which hoses go to the heater back on the firewall, touch each of them after the engine has been running and the blower fan is ON high. TURN the motor off before reaching around because of the fan belts. Both heater hoses should be about the same temperature if water is flowing through the heater core like it should.

    Look at your reservoir tank for coolant. Is it a nice orange? Or orange with a hint of brown tone because of the sealer put in the car in 03 for a recall that GM did to use a sealer again that wasn't put in at the factory. If the coolant is sludgy looking and dark, perhaps oily looking on top, you might have a problem with DexCool that was contaminated with regular coolant and is clogging up. Sometimes the heater cores can clog easily with goop.

    But most likely you have an actuator motor that is dead or stuck. They move the vanes inside the HVAC box inside the car. I can't isolate which one is likely for the temp unless you tell me you have an automatic system with digital readout or a manual system without the digital readout.

    Here's a link to a pict showing two or the actuator motors. Notice they have a small circle at one end in white that's the end of the rotor. So with the key ON, motor off, you can change settings on the temperature, air direction, etc., and the actuators will move. If they don't, people say they come off easily with a couple of screws and you can buy news ones at a dealer or by internet.

    This is a picture I found on the net. It is not my picture. Thanks to whoever took it. It is a heater box without the dash around it. You can access this by taking off the thin plastic covers under the dash, left and right sides. A few screws. Carefully remove them. Notice in the picture you can see the white plastic arms that move th vanes inside the box. I don't know if you can see them in the car or not. I do not know if the temperature blend door (changes from warm to cold) is on the left or the right for your car. I suspect left because on a dual system one on the right would control the passenger side of the HVAC box.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    I didn't read this post before answering the first!

    This might be low water level inside the radiator allowing air to get into the heater core. Then when you start the motor the coolant eventually gets pushed up and through but the air makes a gurgling sound which should leave.

    You'll need to check the radiator by removing the cap when COOL after sitting for at least half an hour to cool down. The radiator should be full. ANd the reservoir should be up to the cold mark and higher. If the radiator is low that means the system isn't sucking coolant back from the reservoir like it should.

    You'll need to find problem source such as leaking water pump, or plastic coolant elbow on hoses to heater, or radiator hose leaks.

    Water from the AC condensing can not drain out of the HVAC box and slosh around when going around corners.

    Water can be leaking in through sun roof drains and collect on floor in car, front and then back. Check carpets for squishing. Check under the front seats. Check inside the trunk.

    Water can leak in through the doors if plastic inner layer isn't sealed, often after work was done in door and the sealer wasn't replaced and they just stuck the plastic layer back on.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • The coolant in overflow tank is a little dark. The top part of the overflow tank above the coolant is pretty dirty looking. When I took cap off radiator some of the coolant came out of radiator as if it were too full. I ran the car for a while and took it for a quick ride. Standing in front of the car, looking at the engine, the hose coming from the radiator on the right still felt cool while the hose coming from the radiator on the left was warm. Does this help narrow down what the problem might be<

    Thank you
  • dewc3dewc3 Posts: 35
    I have a 1997 Buick Lasabre and the temperature readout that is in the car blinks when we start the car up. When we have to turn the heater on, hot air will blow out on the driver side, on the floor like it should but on the passenger side it will blow out cold air. Why would it do that and how can I fix this. It doesn't matter if its the vents or floor or mid level, it's all cold air on passenger side. :mad: :sick:
  • dewc3dewc3 Posts: 35
    I have a 1997 Buick Lasabre, and when I turn on the heater, heat blows out the drivers side floor vent and cold air blows out the passenger side floor vent, why would that happen. Sometimes heat will come out the passenger side floor vents but more than not cold air blows out passenger side. Also the temperature light inside the car blinks for a long time then will stop after like 10 minutes or so could that sensor be going bad and have something to do with cold air blowing out the passenger side floor vents or do I have a seperate problem. Plz advise what can be looked at to fix...thankyou in advance for your help :sick:
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    Is it a dual temperature control system? Is there a passenger temp setting on the passenger door?

    If so it may be the actuator for the passenger broken. It's an electric motor with gears inside that sometimes crack and slip on the axle. Since in a dual control system it relies on indexing to determine how warm it is setting the vane for mixing hot and cold air, slipping means it loses track.

    You can take off the plastic hush panel above passenger legs with about 3 screws and a couple taps holding it to the firewall. It helps to take off the glove compartment door with about 6 screws under the hinge.

    Then you can see all this. Inside the red circle is a plastic motor housing with a rod that connects to the white plastic arm that moves the temperature mix vane inside the heater box.

    With the key ON try changing the passenger temp on the door and see if the upper actuator moves at all. Changing the temp on the main AC unit will move the rod at the bottom that's white plastic (not in picture but would be inside blue square).

    I'll bet your upper actuator doesn't move. It has two little screws on top and one small electrical connector that goes to the programmer box to take it out. But it's not easy. Some people take off the connection to the white arm that moves the vane and put a coat hanger through the glovebox to it and use that to move the vane for passenger from heat to cold. That was on a Pontiac which has slightly different geometry of parts from what I can tell.


    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    If it's a single control system, I have read one person finding the part of the heater core was not getting hot when he took off the cover under the dash. So he flushed the heater core, gently I hope, with water and compressed air, and was able to flush out rusty looking stuff and get all of the heater core warm.

    Apparently the part that was cold was what the air to the passenger side went through.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • dewc3dewc3 Posts: 35
    Thankyou for your response. And yes it is a dual control, there is a passenger temp setting on the door for that side. You said its not easy to fix I believe, but from the picture im looking at once I get to this part what are the steps in replacing this as I rather not use the coat hanger Sometime in a blue moon heat will come out for the passenger side but very rare...Would you happen to know the price in buying one to replace and what do I actually ask for as far as a replacement? I really appreciate your help as this is the surest answer I have heard cuz I have heard something bout an actuator thing once before so anymore help you can provide is very much appreciated
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    First, you must diagnose to be sure that's the bad part. If you get to the part and can move the white lever connected to the actuator to change it with your fingers, that means the gear inside the actuator is broken; it shouldn't move.

    Or you change the temp settings with the key ON and the actuator moves, but jerks or slips (the wheel inside slipping on the hub since the wheel has cracked), then you are ready to replace.

    The two little screws on top are difficult to handle and replace, according to people who have done it. One fellow tied fish line through the socket and the screws in case they dropped, but that's the level of difficulty.

    Go to Pick Buick. Then 1997. Then go to Heat and air conditioning. Then go to A/C vacuum actuator. Your system is CJ2 so I think you want the 2nd one that says CJ2 near the end. Note it says vacuum actuators for the group, but those are electrical. Because of shipping costs with rockauto, you might check your local dealer or other places on the internet, such as

    I would probably pick the local dealer source because if I got the wrong part, I might be able to return it for the right one. Or take off yours and check the parts number with the one on the rockauto or gmpartsdirect or what you get at the dealer.

    To verify the code RPO for your system, look at the spare tire cover under the mat in the trunk. The white tag lists all the options and base components for your car. You should see CJ2 listed instead of C67 (the manual temp control system).

    I think I just saw someone's writeup on how to do this replacement...

    Let us know what you decide.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • I have a 1993 Buick LeSabre with the automatic heat/ac controls. The outside temp has been reading 199 degrees, and recently it would only blow hot air out of the passenger side, when the temp controller was turned up to 90 degrees. If turned down to 85, it would blow significantly colder air. The drivers side has been cold no matter what. This has been going on for about a month.

    This week, the blower has been fading in and out, and I was thinking it was the automatic fan control, though it would do it regardless of fan setting. Then the fan quit altogether. Yesterday it blew faintly for about 2 minutes, then out again.

    Wow, bad week for this to happen.

    I saw that "sturgis larry" replaced the temperature sensor, and all was good again. My question, was that the external temp sensor, by the grill, or would that have been the rods under the hush panel? Also, do I need a new blower motor, or a sensor?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    Could be fan motor going out.
    Could be blower control module going out.

    Did you try changing the fan speed setting manually?

    Did you try hitting gently the fan housing on the firewall under the hood. A sticking, bad bearing will let go and the fan will often start running--a temporary fix until it can be replaced.

    The temperature sensor in front of the radiator support can be disconnected and reconnected to see if corrosion on the contacts are causing the problem in the reading. It's a fairly cheap fix.

    The blower control modules can be had for 90$ on ebay. First directly connect blower motor to battery with a fuse to be sure the blower motor works right before replacing the module.

    Or get a module, temp sensor from a recycling yard.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • 1994 Buick La Sabre.

    It has temp cold warm-cold slider. It has PB's for functions (yellow lights in buttons). So I'm saying it is manual; ie no digital readout of setpoint or actual temperture.

    It does allot of stuff and it has been doing it for over a year.

    1. most of the time system works fine. yellow pb lights respond to pushing them.
    2. sometimes all yellow lites go out and system dead.
    3.sometimes you can hear relay(s) chatter over on the passeners side
    4.somtimes the AC compressor will start on it's own.
    5. Fuse looks fine.

    Flappers seem fine.

    thanks for any help
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    First place I'd go to would be the ground buss on the driver's side under the door sill plastic next to the carpet. The ground buss is wrapped in electrical tape against the bundle of wires that go toward the back of the car.

    Does the car have anything else that gives symptoms when the heater control acts up? You might try just hitting on the floor in that area to see if you can affect a corroded contact.

    I have a 93 with the heater occasionally losing control--the unit defaulted to AC compressor engaged and cooling fans running for it but the controls didn't change anything. The electric door locks also wouldn't work while this was happening, so my conclusion was that the ground buss was common to both problems. I didn't get to find out because my wife made me trade it for a new bright red one before the problem started happening more often.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • I have a 1998 Buick Lesabre Limited with 120k miles. I only get air and heat from the windshield and the floor. Nothing from the vents at all. What is the problem?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    Check the black plastic 1/4 in line for the vacuum to the heater unit from the intake manifold to the passenger side rear and to the front of the car down under the right front fender where there's a vacuum bottle that holds vacuum for when the motor loses vacuum at open throttle.

    The black plastic line connects next to the big rubber tube from the brake booster.

    Another check is run motor. Turn off but leave key at ON then switch different buttons on the heater control unit. If there is vacuum, you should hear the diaphragms moving vanes between different settings. You should have enough vacuum stored for about 10-15-20 seconds of changing.

    Then if you're getting vacuum inside,

    I replaced the plastic multiconnector with 1.25 inch pieces of 1/8 inch internal diameter gas line, free from friendly scrap box at NAPA.
    Others have used aquarium tubing.

    The black nipple layers inside the connector pull closed and block vacuum to the AC diaphragm first, with age and heat.

    Take off the under dash thin plastic panel. Take off the glovebox door at its hinge with about 7 screws. Then you have good access for arms and light to the programmer box sitting anagled on the corner of the HVAC box. The programmer is held on with 2 screws, a multiwire connector and on top a little connector that goes to the electric actuator on top.
    There is a plastic link at the bottom that comes from the electric actuator inside the programmer and snaps onto a wire rod with grooves on it that sets the throw of the lower vane for the passenger side IIRC. Top electric is for the driver vane temperature blend.

    The blue plastic vacuum line goes to the actuator for the AC vane that closes and forces air that would go to defrost to come out the dash vents.

    You can check for movement of the 4 diaphragms by taking off the plastic underdash on the driver side--all 4 are on that side. The back of the diaphragm is open and you can feel the diaphragm pull if you have motor running and switch the dash settings to different modes.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • I have a 2003 buick regal ls. It has the digital dash, with separate heating and cooling for the passenger. About a month ago the heating system went haywire, no heat to the drivers side. following the tips posted on this site I began to troubleshoot the problem. !st I flushed the radiator. That seemed to fix the no heat to the drivers side. But the temperature coming out of the passenger side was 5 to 10 degrees cooler than the drivers. Again back to the forums. Decided to try charging the air conditioner. I put 16 ounces of freon in it. Violla the heat coming out of system is the same temp.on both sides. When starting the car I noticed the heat coming out of the vents was 120 degrees (when the engine warmed up) as the cabin warmed the temp coming out of the vents slowly came down to 90 then 85 and pretty much stayed there. I just wanted to post here to thank everyone for their help. I would have been lost without it. ;)
  • dcr2dcr2 Posts: 1
    Ext temp always reads 38 degrees. Replaced sensor in front of radiator. No help. I'm out of ideas.......
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    edited May 2010
    >louisiana1 asked:
    Whats up imidazol97? I have a problem with my 98 Buick Lesabre. Last Friday my blower just stop working with no warnings all. It was working fine 2hrs prior. I put a brand new blower on it and the new one wouldn't come on. Since my old one was already off, i got it tested Autozone. It spent like a champ. I checked all fuses and all of them lit up. I even check the ones on the passenger side and under the hood, they all tested positive. Later, I got a resistor off a used Buick and hooked it up and the blower still wouldnt work. Next, I got an a/c switch off a used Buick and still nothing. The blower still wouldn't blow. I've taken it 2 several mechanics and they're dumbfounded, they can't find out whats the problem. Im just tired of spending money and my problem isnt being fix. I'm in desperate need of help. Can you help me?

    You need to check with a meter to see if you are getting power to the resistor pack with the key ON and the blower motor switch ON. If you had the relay center loose and put in a new resistor, you sound like you are capable.

    Since you say it had a resistor instead of a blower control module in the hole, I assume it's the standard AC without the digital readout and without dual controls.

    Those have a relay in the relay center that turns on and off the blower circuit.

    I believe it's the relay at the left side of the relay center-the passenger side. It's the third from the left (compressor, horn, blower relay).

    Most of those relays are the same part number, so the second one which may be cooling fan can be switched to the passenger side to see if the blower motor runs.

    Use a knife blade underneath to lift the flat spring catch the snaps over a prong to hold the relay in to pull the relay out. You might try checking for power on the brown wire which should be hot with ON. --from fuse 5D in IP fuse block, 25 A.

    the output wire is light blue and goes to the resistor pack.

    That relay should be the same part number as the horn and compressor and is a single pole relay.

    Another relay is involved and has a Dark blue wire and a Red wire to the two power connections and the out connection is purple and goes the the blower motor.

    This should be the relay in #5, the fourth from the passenger side. It is a single pole double throw. It connects either to the output from the resistor pack OR to a 30 amp red lead direct from power for HIGH speed. It's called the high blower relay.

    On these relays check the colors I gave you because the book has the circuit diagram mislabled as to which is the blower relay and which is the high/normal speeds relay.

    That fuse for the REd wire is in the underhood fuses--the big ones and is 30 amp. It's #3 fuse. I think there's a label on the inside of the relay cover?

    There's a third fuse involved and thats' in the IP fuse block, #5A called the Auto AC cruise. It appears to provide power to the heater and AC control on the dash.

    The high speed blower relay might not be making contact on their of the two contacts. Normally people have either the low speeds or the high speed working.

    But you can use a fused jumper on either of those relays for the input/output power leads and see if the blower starts to run. But best to use backprobing the contacts with a meter grounded to battery negative, to see if you got power where it should be with key ON and blower set for one of the lower speeds.

    You might use meter to check that ground on the blower motor is actually grounded to the negative.
    This info came from a 98 Factory Service Manual.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • louisiana1louisiana1 Posts: 6
    My a/c switch is manual and its not digital. Mine have levels. I tested the resistor with a testor and all three coils tested positive.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,245
    >I tested the resistor with a testor and all three coils tested positive.

    Measuring resistance won't check what needs to be done.

    You are looking for where the postive battery current is delivered along the steps in the line to the starter motor. When the key is ON and blower switch is ON, does power get to the purple line on the blower motor?

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • louisiana1louisiana1 Posts: 6
    No, power isnt getting to the purple wire when I turn the key on. I also tested the brown wire with the light blue wire and still no power.
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