Buick LeSabre Heating / Cooling



  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    Do you have the digital readout AC or the standard AC?

    Do the lights on the buttons work in the control unit?

    Does the temperature go full hot when you turn the temp way UP? After the engine is hot of course.
    Does the temperature go down to cold?

    If you have dual controls, does the passenger side modulate the temperatures?

    Are you sure the AC compressor is working? I'm assuming that you are in the US and most of us are needing cooling and not heating.

    Open the hood with the motor running and touch the metal line toward the dash after the metal line does an upside down "U" to go over the accumulator? Then touch the big metal line going back toward the accumulator from the dash. Both should be cold.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • tvaleriotvalerio Member Posts: 3
    A.C. compressor is a new Reman unit. System is fully charged Blows ice cold. Standard Ac readout. All the lights work. Fan switch works fine. System switch,s from floor to mid level to defrost so I know that I have vacuum to controls. What doesn,t work is the thermostat. Setting could be 60 or 90. All I have is Ac. It does switch to vent when asked to. Pass. side switch is NG. I need to replace that.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    edited August 2010
    Thank you for the information. That would have helped to included the info in your first post.

    How do you know the passenger switch is "no good"?

    >I opened a door in the heater box [non-permissible content removed]. to allow A.C. to operate. I now have A.C. but no control of the temp.

    What does this mean? How did you open a door?

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • michaeld8626michaeld8626 Member Posts: 2
    edited August 2010
    hi i bought this buick custom with 3800 with 101,000 miles hve had no problems with it till now . i opened the hood an noticed the top raditor hose had collasped., sucking together, but the car wasnt overheating. a week or so later i changed the hose an bleed the system, ther was dex cool in the car thats what i put back in, well the car tryed to over heat . temp ran up as i pulled into drive at 250. well i opened the hood no steam, i looked at the coolant bottle it was still full. next day i checked the return line coming from the recovery tank it was clogged . i unclogged it removed the overflow thank washed all the brown gunk . i guess this is the sludge from dex cool? remounted the bottle refilled it , rebleed the system reving the engine up to 2500rpm couple time , thought i had removed all the air.but the temp needle keeps going up a little. the electronic read out saying up an down rapidly temp runs up to 230.please help is it the thermostat? or clogged cooling system>?if you guys think its clogged what is a good product to flush the old gunk out?thank you guys for your help
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    edited August 2010
    > i guess this is the sludge from dex cool?

    Don't fall into the blame DexCool myth. It's been perpetrated like a Democrat/Republican political slogan.

    Someone added regular antifreeze to the DexCool. That's what causes the sludging. The formula for DexCool changed early in its life because of a problem with an antioxidant deteriorating. Since then the formula is the same as the Prestone Mixes with Any Color stuff. Check the 4 ingredients on the labels of each.

    Frankly, I'm not sure of a cleaner to put in and use to remove the DexCool. But I'd try. The drain for the radiator is on the bottom of the radiator. There's a hole in the air shield for a socket of a certain size to up to it. There may be a bundle of wires hiding the drain.

    I would expect the sludge to affect the thermostat and reappear any time you run the car after putting in new antifreeze. I definitely would get it cleaned. I would consider paying a shop to disconnect the proper lines, remove the thermostat, and flush it with a strong cleaner that they then flush out.

    I changed my DexCool about every 36000 miles by removing the lower radiator hose and draining, and refilling with water, running to circulation temp, and draining. I did that 3 times. Then I put in new coolant. I have had no problems per the myths.

    I judge that deteriorating antifreeze would have been a problem whether the other OAT types were used of DexCool.

    There is a belief that a car that's not run to temperature so that all the coolant gets up to high temperatures occasionally has a problem with bacteria deteriorating the coolant package. That may be speeded if there's air in the radiator or system to mix with the coolant.

    I would have it professionally flushed as my personal choice, where they use the air mixed with water and reverse flow to try to agitate and get everything out.

    I would refill with Prestone Mixes ...Color, just so you personally wouldn't worry about the DexCool myth.

    Be aware that the car had an organic sealer put in from the factory such as finely ground organic material, to seal leaks. That also gives a brown color. After cleaning and draining, you should put in another tablet or two of this organic sealer.

    Also, if the intake manifold on the car is original at 101,000, I would have the gasket on the END of the upper at the throttle body replaced with the thicker gaskets that are the usual replacements. You might consider removing the throttle body to clean inside (black oily gunk collects normally) and replace that gasket. The original gasket GM used is thin. The Upper intake may warp slightly with heating and cooling and the gasket can't maintain a seal causing coolant leaks. If you have a good shop, you might combine the coolant system cleaning and throttle body gasket replacement.

    Eventually the lower intake gasket between the metal lower and the heads may develop coolant leaks. But that's a larger repair job, and once it's done with quality replacement parts, you're good for 300,000 with good oil changes.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • michaeld8626michaeld8626 Member Posts: 2
    hi,imidazol97, thank you very much for your input , i will do what you have suggested, i am not a mechanic,just a truck driver that used to build hot rods years ago in my earlier years.
    i really do thank you.i was stuck at that point scratching my head., but you have cleared things up for me .
    thanks again!!!
  • retiredwrenchretiredwrench Member Posts: 1
    I am a retired technician and had the same problem happen to mine,I pulled out the wiring schematics and started to go thru the tests and while doing so found the problem to be the blower motor plug (2 wires) at the firewall/blower motor.I discovered that by holding at a angle the motor started working ! I went and found a used pigtail and spliced it in my harness and problem solved ! :shades:
  • billnmd2006billnmd2006 Member Posts: 7
    My 1994 Lesabre Custom only blows air out the floor and winsheild vents.No air comes out the vents in front of you. What can the problem be? Is it a mode switch?

    If so where exactly is it and what does it look like?? Can anyone give me step by step instructions on how to fix the problem?

    Any help would be good.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    edited August 2010
    Did someone replace spark plugs or work behind the motor recently?

    That years has the vacuum storage tank on the firewall behind the motor. It's shaped to look like part of the relay center. The rubber vacuum tube to the tank is always getting pulled loose. Check there first.

    No vacuum at all leaves the system in defrost with some air coming out the floor vent for safety to clear the windshield if needed.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • theabbottheabbot Member Posts: 4
    I replaced the motor blower about two weeks ago. Everything was fine. Cold air was great. Well, I still have cold air but now, when I have the air on and try to accelerate, the engine seems to have difficulty going into higher gears. The rpm's increase, but the car doesn't pick up speeed, and is reluctant to change to higher gears.
    Any ideas?
  • tvaleriotvalerio Member Posts: 3
    The blower motor has nothing to do with the transmission. You need to recheck all the wiring near the blower motor. Is the ECM in that area of the dash ? Did you disconnect any wires while replacing the motor and forgot to reconnect them?

    If all of the above is correct, check the fluid level of the trans. You may need to have the filter replaced in the trans, or you may have a larger problem. You didn,t say what year Buick you have. The newer years have a trans that the shifting is controlled by the computer
  • stephen987stephen987 Member Posts: 1,994
    Hmm. Any vacuum lines involved?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    edited August 2010
    >when I have the air on and try to accelerate, the engine seems to have difficulty going into higher

    What year is your car?

    Like stephen I wonder if there' some vacuum control of the transmission involved. Even changing the vacuum for the motor could affect transmission operation.

    Check the rubber connections on all vacuum lines going into the upper intake manifold. The rubber can deteriorate and crack, leaking vacuum, with age and heat.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • theabbottheabbot Member Posts: 4
    Thanks for the replies!
    My vehicle is a Limited, year 2000. I will check those connections as soon as it stops raining today.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    Your car has no vacuum links to the HVAC system. I believe it has no vacuum controls for the transmission.

    How many miles on that car?
    When did it have new plugs (use AC Delco and new wires?). If it's at 100K, it's past due because of the 10 years.

    Also check the coils. I would suggest removing each, measuring the primary resistance and secondary resistance and comparing all three coils.

    While they're off check the contact areas for corrosion. Coat with dielectric grease for reassembly.

    Check the connection at the plate under the coils which is the ignition spark control unit. Loosen the connector and move to make good contact.

    Next would be to check the fuel pressure at the fuel rail. Ideally, get or take loan of a gauge set with a long enough tube that you can tape it to the windshield while you drive the car. See if there's a difference when the AC is on and the car is running nice and hot. You might have a fuel pump wear problem or fuel filter clogging.

    What does the car do for gas mileage at highway cruise speed compared to what it used to get? If you have the digital readout that's easy to compare.

    Diagnose. Don't replace without certainty there's a problem.

    My bet is on plugs and wires. The additional load of the AC causes leaking spark or poor plugs to show up.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • muddman50muddman50 Member Posts: 3
    I have a 97 LeSabre Custom that I have changed the auto a/c controller on and I'm still getting a fading of the display but everything is functional with the controller. I can change vents, temp. up and down, auto to manual control I have input from the steering wheel that raises temp up and down but I can't get rid of the fading in and out of the display. Any ideas?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    There used to be a topic about a Regal problem with the displays fading. The one layer of the unit has rectangular resistors that have failing connections to the circuit board. Soldering them again would fix the problem. I've never taken out my display in my 98 LeSabre. It sort of works. But I believe it looked similar to the one in the Regal topic on how to do it, that I believe it has the same resistors.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • clearlakeclearlake Member Posts: 11
    In my case (99 LeSabre Limited) I had to patch around the small plastic "distribution box", DB, that is in the upper left corner of the "programmer box", PB located behind the glove box. The common problem with the DB is that the "nipples" on the outer or "outside" half of the box get soft and collapse, shutting off the vacuum from the programmer solenoids to the heat/air control doors ( I forget the official name for these things).

    I wish I could figure out the way to include pictures for you and others to see. Let me say this; I had to remove the glove box. Watch for the light and oil change reset button, if applicable. After removing the glove box, you should be able to see the fairly large programmer box, PB, the DB at the top on the left, and all of the connectors and colored plastic hoses coming out of the DB. Note that the pink line(in my case) coming in from the upper right area, looking through the empty glove box opening, provides the vacuum supply to the programmer, inside the PB, and its associated solenoids that clamp down on one or more of the colored lines going into the back side of the DB. If the connection can make it through the nipples and out of the outer portion of the DB the appropriate doors open/close.

    I did disconnect the pink vacuum supply(it's long and has some slack) and hooked it to a line outside the DB and voila! cold air came out of the dash vents. I don't remember which line I tried, but if the DB is the problem, something will change!

    I worried about the large red and grey electrical connector (from the dash switches, I suppose [my car has the automatic temp. control]) and a rod/connector( probably to a control door somewhere) at the top left of the PB. I checked everywhere I could but no help. Work SLOW and use a small screwdriver to release the red/grey connector. It snaps back together with no problems.

    With the PB removed and on the breakfast table I was able to take the case apart and then the DB comes out. I then could see that the nipples had in fact become so soft that they were collapsing.

    I bought about 3 or 4 dollars of vacuum hose, somebody suggested aquarium tubing but nothing fit for me. After cutting the tubing,see below, take some with you to assure a tight fit. ATTENTION you must note all of the inside to outside color connections and their locations/orientation on the DB before cutting them. I cut all of the vacuum lines at the DB, both on the PB side and the outside. Leave the DB together and oriented in its original position to help keep the tubing color alignment straight. I looked at all of this much longer than most people would but I have a record of doing things over more than once.

    Some might recommend a second hand part, rather than this work around. Remember, if it failed once, it's likely to do it again and I sure don't want to go through the glove box again unless it's to just fix a tubing connection/tape job. Now that I'm thinking of it, why wouldn't you leave an extra amount of vacuum hose where you attached to the outside vacuum lines in case it slipped off. At least that end would be easy to fix.

    Going back together was much quicker. AND it's still working in Arkansas, where my son lives.

    If you have gotten estimates for this problem, you know that new parts and labor can add up to more than $2000. I know this to be a fact and have the paperwork. I received estimates of repair at one in my area that contains the word "Christian" in the name that gave me a repair estimate of , let's say just over $2000 up and including let's say, mote than $2700 ; fixing something other than your car; probably your pocketbook. I also must say that I paid $100+ for this estimate. his estimate included the dashboard electronics AND the programmer too. The price astounded me. No evidence was found that the above mentioned shop had even opened the glove box. When questioned whether or not the basic A/C tests had also been run, which was what I had originally requested, the shop manager went into the shop to question the mechanic, returned after more than 10 minutes, and told me that the mechanic couldn't remember.

    I hope that this saves you and maybe others some money. If so, I hope that you pass it on. I give this freely to individuals and to professionals. I hope that the pros charge appropriately, with the disclaimer and explanation that a "work-around" was used. I think a pro should charge no more than $100-$400.
  • wizzard1222wizzard1222 Member Posts: 4
    Thanks for the description. My 89 LaSabre Custom has started w/the same air flow issues. This came after I was told that my EGR was causing power loss during acceleration. I'll check the vaccuum line in the engine compartment as well.

    By the way, I think adding images can be added by the "IMG" button below the post a message window.

    Thanks again.
  • wizzard1222wizzard1222 Member Posts: 4
    edited August 2010
    sorry about the double post...see below
  • wizzard1222wizzard1222 Member Posts: 4
    After reading many of the forum posts...I started checking the AC lines, engine compartment and under the dash for the vacuum lines and the proper operation of the AC lines. (213,000 miles & rolling...approx 33 mpg on the highways...60 mph)

    After checking the vacuum lines behind the glove box & finding that I DID NOT have any vacuum...the search continued into the engine compartment.

    I was having troubles with the EGR valve...cutting out on power acceleration & making a middle tone whine.
    I also noticed that this area had been extremely hot because some of the plastic protective coatings on some of the electrical lines had melted !!!

    I did not notice or think of a vacuum line leak when I noticed this melted plastic. Of course, thinking back in time...I remember a few times of smelling plastic and/or electrical odors & wondering where that could be coming from....

    I tried to attached a photo of the collapsed vacuumm line near the EGR valve. I sourced a replacement line from the salvage yard.

    I removed & replaced this collapsed vacuum line & the AC 'bin/door' started working immediately !!!

    Thanks again for all of the former posts about this issue. I am sure it would have been hard to find this valuable information from the service manuals (Haynes...etc.).

  • yayiyayi Member Posts: 4
    I have a 2000 LeSabre that stopped blowing warm air, it only blows outside air. The heating core works, and there are no cooling fluid leakks. I suspect it's the vaccum system. How do I locate the vaccum lines that regulate the heating system?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    I do not understand what you mean about it blows outside air and stopped blowin gwarm air.

    Can you describe your symptoms further as to what's happening.

    I can help you about the vacuum. There isn't any. The HVAC box is controlled by 3 or 4 electric actuators if dual control system. They are easily found just taking off the hush panels and ducts under the dash with some screws. The actuators have a white rotor in the middle that makes it easy to tell if each is changing with changes to the control on the dash.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • yayiyayi Member Posts: 4
    Well, what I meant to say is that when I turn the heat on, I get no heat. The fan works just fine.

  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    Thanks. I went back and reread the original post. My question is about the air flow. Is the air coming out the floor vents or the dash vents or the defroster as you change the settings?

    Then when you change the temperature setting, does the air coming out the chosen vent opening change temperature?

    I suspect that answer is "No." That probably means an electric actuator is not working. Does it change temperature if the AC compressor is on and you are cooling air during the hot daytime?

    An alternate possibility is that there is no water in the heater core. This could be because of a low water level in the radiator. Check the level in the reservoir. When the engine is cooled down some after driving, open the radiator cap at the radiator by pushing down and turning. Be sure the radiator is completely full. A low level here can move an air pocket into the heater core; sometimes people will complain that they get heat for a time then it's off. Or they hear noises as water sluices through the air in the heater core.

    If level is low in the radiator, fill to top with antifreeze mix. Put cap back on. Then run engine to temperature with a longer drive so lower radiator hose is warm. Then run motor at 2500 rpm for 15 seconds at a time. I do this with the front of the car uphill slighty on my drive apron in front of the garage. Repeat 4 more times.

    You could drive car at high speed on road in 3rd gear, I would think, to effect the same result of pushing the air bubble out of the heater. Then bleed air at the thermostat housing with the little cap on top until antifreeze oozes out meaning all the air is gone from that location.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • yayiyayi Member Posts: 4
    I checked the radiater level and it's full.
    Yes, air comes out the floor vents or the dash vents or the defroster as I change the settings. But when I change the temperature setting, the air coming out the chosen vent opening does not change temperature.
    I get cool air when the AC compressor is on during hot daytime.

    Does that indicate the electric actuater is not working? If so, how can i get to it, and how do I repair it?

    Thanks again for your help.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    If your car is a Custom with the standard AC controls without a separate passenger and drive temp control and without the digital readout, I think this is where your actuator is, #2. That one moves a blend door that allows more or less of the air to go through the heater core to be reheated after passing through the AC cooler core.

    #2 actuator

    Under the passenger side of the dash, carefully take off the plastic quiet panel and the built in ducts in it. Then you can see the actuators. They have white plastic hubs and show easily to see if they rotate when control positions are changed on the dash panels with the key ON.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • muddman50muddman50 Member Posts: 3
    My car is a custom but it has pass. controls for Heat/Air and it has digital readout
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    Then the driver temp actuator will be on the driver side of the HVAC box.

    driver actuator

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • yayiyayi Member Posts: 4
    My car is a Custom with the standard AC controls without a separate passenger and drive temp control and without the digital readout. I will start work on it shortly.

    Again, thanks for all the help.
  • sed55sed55 Member Posts: 3
    When I start my 94 LeSabre Limited, the A/C fan will not come on 99% of the time. The Dual Automatic Control will be dark, no lights at all. After driving about 5 minutes or so, the fan will begin to start then stop several times before finally coming on. The control head will then show the blinking set temperature and the Dual and Defrost lights will be on. The air is now blowing out of the windshield vents. If I repeatedly and in rapid succession press the Auto burtton, the air will eventually come out the dash vents. Is there anything I can do to try to fix this? The buttons on the passenger control have to be pressed repeatedly to move the indicator. On the main control, the buttons must be repeatedly pressed to take effect.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    edited September 2010
    Your problem might be a defection head unit or control unit on the dash. I would suspect, however, a ground problem. Are you in a wet climate with snow or lots of rain that carries into the car and wets the carpet near the door as the foot drags over it?

    I think the AC control grounds at the buss that's under the door sill plastic right where your feet go into the car. It's bundled with other cables and wrapped with tape. They corrode. You might try hitting against that area when the AC control won't work and see if things make connection.

    Does anything else not work at times, like the power door locks?

    The blinking could just be a reaction to having the power go on and off as the connection is made.

    AC units are the same for 92-94 leSabres and 91-94 Park Avenues. You might pick up a couple from a junkyard and see if they work better. They should be an easy removal after pulling the plastic trim off the front of the dash.

    You might also have a problem with the blower motor control module which changes the voltage to the motor to vary speeds. This replaced the resistor in older cars with set speeds. It's a power transistor and some circuits. Follow the power leads from the blower motor. It will be close by and will stick into the tunnel where the blower motor pushes the air; the air movement cools it. These sometimes fail with odd speeds compared to the 6 or 7 speeds manually selectable. Sometimes they keep the blower motor on even when the key is turned off, draining the battery.

    You can connect the blower motor directly to battery power and a ground with a fuse to see if it runs fine at full speed. Motors wear and stick and do funny things with age and detrioration.

    The air flow direction may be similar to the problem with the connector on the programmer box on the corner of the HVAC box under the dash. The vacuum sucks the soft plastic closed. It usually happens to the dash vacuum tube that closes off the air to the defroster to make it come out the dash front. If the air won't come out the dash at first, see if it's coming out the defrost.

    I can give a link for bypassing the softened connector if you find that's what's happening. It also could be just poor vacuum due to rotted or cracked vacuum lines under the hood or a cracked vacuum reservoir tank that's losing vacuum. When there's no vacuum the unit go to defrost direction for safety.



    2014 Malibu 2LT, 2015 Cruze 2LT,

  • sed55sed55 Member Posts: 3
    Thanks for the reply. I failed to mention in my original post that I have had 3 control heads in this car ... 1 was even purchased 'new' from an AC-Delco parts distributor. I am beginning to doubt it is the Control head. When the system is off, there is no exterior temp display - with any of the heads that were in it. Truly, it is as if there is no power to the unit then all of the sudden it comes on. The control is the same as the 91 - 94 Park Ave? I dont think that there is a fan motor issue since the fan does run. Is there any way to test the control head? Thanks again.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    You have had three new control heads in it. I doubt it's the control head.

    I'd check at the buss ground connections. I would take a look at the one of the left--check my pictures I linked. They're not hard to get to.

    My 93 had started occasionally losing control of the heater (manual AC) and the system reverted to defrost and the AC turned on. Probably the default was the compressor on. The lights on the head did stay on. At the same time the door locks would quit working. Then after a while driving or after parking the pair would start working again at the same time.

    I never got to troubleshoot it by checking the buss: my wife made me trade it for a pretty red 03 leSabre when they came out with a pure red again.

    If you are enough of a cobbler, it would be interesting to connect to the power lead of the AC head and use an LED light to show when it had power and when it didn't have power.

    OR I think take the ground wire for it and parallel a 2nd ground lead along with the other and see if that eliminates your symptom.

    I think you're into a diagnosis stage here.

    The only other thing I can think of is the ignition switches might have a separate contact that's worn and is making and breaking contact. I never have physically checked to see how many different contacts are in the ignition switch--that's the actual switch down on top of the lower steering column and not the key cylinder at the top.

    I do know a few people have had them wear out with certain things dying while driving, but I can't remember if that was the car cutting off motor-wise or if it was accessories.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • muddman50muddman50 Member Posts: 3
    I finally got around to looking at the control board and you where correct there were 4 pink colored round not square 120 ohm resistors that had signs of excessive heat and they basically unsoldered themselves thanks for the fix. Working like it was new.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    >round not square 120 ohm resistors that had signs of excessive heat a

    Thanks a lot for posting back about what you found. It lets me know I steered someone the right way and lets people reading know what worked if they have the same symptoms you had.

    Thank you.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • jj14jj14 Member Posts: 2
    It seems like im having the same problems most 94-98 lesabre owners are having..I need help!

    First off I have the digital control w/ passenger side climate control as well..

    When I start my car the ac/heat control unit will blink for about 30 seconds..when its blinking nothing but cold air will blow in the winter and nothing but warm air will blow in the summer...when it finally stops blinking in the winter on the driver side will get heat, the passenger side will be ice cold..in the sumer the drivers side will get air sometimes and the passenger side will be hot...

    I have been told that it is the AC heat programmer by a local shop and I have also been told that it is a blend door actuator by my mechanic..these are 2 big differences..also when I turn the key (without the motor on) i hear what seems to be my blend doors moving while the ac/heat programmer is blinking...

    I have read many forums and it seems to be the actuator but I dont know which actuator to get..I have a friend whose parting out a 94 lesabre so I could just get it from there if I knew which one to get
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    edited December 2010
    I can tell you I've had the same symptoms. The HVAC box under your dash uses vacuum actuators to change the path of the air flow. But it uses electric actuator motors that move wire rods and move doors inside the box to change the temperature by moving blend doors that make more or less air go through the heater core for heating.

    You can take off the hush panel under the passenger side dash. It has about 3 screws holding it to the front of the dash and two little nuts that hold it to the firewall above the carpet.

    You can then see if you are able to lie on the floor the actuator on TOP of the HVAC box with a metal rod that attaches to a white plastic arm that moves the door inside the box. If you can move that arm with about the force to move a library book sliding it on a formica countertop, the gear inside the actuator is cracked. That lets the gear slip on the gray hub. It's the gray hub that moves the metal rod. I took mine out, disassembled the actuator, glued the nylon gear to the hub, and put it back in after drying overnight. So far it's working. Note that the gray hub and arm outside the actuator box has a tab that operates in a slot of about 180 degrees. That limits the movement; be sure to keep the tab in that slot.

    This is the HVAC box with the actuator circled on top. The bottom actuator goes to the programmer box and is for the passenger. You should be able to turn the key ON and operate the temps on the controls and make those actuators move. You may be able to tell the top one slips on the hub.


    The actuator looks like this:


    If you glue the gear in place, consider the gear's movement range so that the crack is not in the movement allowed.

    Replacement actuators are available at different stores and rockauto.com. I am thinking the actuator is in the $50 range.

    Some have snapped the wire rod out of the white plastic (just push backwards--it snaps into a groove) and held the heater vane in place with a coat hanger to manually move the temp door.

    Better access to the repair site can be had if you take off the 6 screws along the bottom of the glovebox hinge. It all drops down and you've got great access.

    Good luck. Hope this info helps. You do not need a programmer box. I am 99.99% sure you'll find you can watch the actuator slip or make it move by pushing on the metal rod.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • wizzard1222wizzard1222 Member Posts: 4
    Thanks imidazol97: Thanks for the great experience sharing & photo. That's very helpful since I have not yet gotten to the underside of my car.

    Thanks for sharing
  • sed55sed55 Member Posts: 3
    How much for the digital control out of the '94. I need to keep on trying them until I can finally get one that a) turns on all the time and b) changes when I press the button. Mine I have to pound on the buttons to get them to change and forget about any temp changes with it. I have not been able to get a viable cause other than to kerp on throwing controls into it. I have tried three already. This is a '94 LeSabre.
  • jj14jj14 Member Posts: 2
    Thanks for the detailed instructions!!

    I have looked at rockauto and looked at the actuators. I have a CJ2 code for my buick so I need the part #16141822 which is, like you said, in the $50 range...

    my question is..if I get my mechanic (who also said I needed a blend door actuator) to fix this, will I be able to get hot heat on both the driver and passenger side in the winter, and cold air on both sides in the summer? Also, will this eliminate the blinking on my control unit?

    Again thanks so much you have no idea how much I appreciate it! :)
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    >I be able to get hot heat on both the driver and passenger side in the winter, and cold air on both sides in the summer? Also, will this eliminate the blinking on my control unit?

    I can't be there to diagnose, so I can't guarantee.

    If you watch the movement of the actuator arm when you change the settings for driver side from cold to hot, you should be able to tell it's not moving the full range due to slipping. When moving, you should be able to push your finger against the rod to help it move one way or the other. And that should give you full heat or full cold.

    That was my diagnosis. I could move the arm with moderate finger pressure. Many Pontiac owners have had the same problem. Theirs is harder to get to the two screws holding the actuator in place because of the placement of dash and shape of the instrument panel.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • atxcaratxcar Member Posts: 3
    Looking through the threads I think my heater / AC control unit is bad, but would like a second opinion before replacing it. It's a 1993 Buick LeSabre, Custom with the non-digital control with push buttons that are supposed to light up; a slide lever for the heat control; another slide switch for the fan; and a rear defog button. Not a dual unit. Seems to be AC Delco part number 15-71887, oem 16145214.
    The car is fully maintained, but with high miles (100k+).
    At the moment, it wants to run the the AC through the defrost, but I can push the button to go through bi-level and it will do so with cold air for a while (time varies). I cannot turn it off by pushing the "off" button. None of the buttons seem to respond properly, and it seems to switch between settings randomly with the air flowing to that selection. Sometimes the buttons light and sometimes they do not.
    Initially I had to fix a ground disconnect at the battery and another loose (smoking) ground at the top, middle of the firewall between the relays and big fuses. I also had the AC system recharged. Prior to the ground fix, the buttons would light up in a circular pattern, switching the controls as they rotated. At least now that has stopped. The driver side interior ground seems good too. The car did have an aftermarket alarm in the past.
    The AC does blow cold and I can move the temp lever to have it blow hot.
    The problem is not being able to turn it off and not being able to select where the flow goes properly.
    Any other ideas or suggested tests? Could it be vacuum or the reservoir? The other part by the glove box?
    If odds are that it's the control, which other makes and models would have the same control unit? 91-94 Park Avenue? What else? These things seem to be getting harder to get.
    Thanks for your help.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    It does sound like the electrical control unit in the dash might be at fault. You say you're cleaned the ground on the driver side under the carpet under the door sill? There also is one on the passenger side. I do not know WHICH one is the ground for the heater AC unit.

    I do know my 93 had started losing control of the heater. It would go into AC mode with the compressor running and the power door locks would not work. I did not get to isolate which ground was the one before we traded it for a newer leSAbre.

    The dash control unit is for 92-94 leSabres and Park Avenues including Ultra according to RockAuto--when you click on the blue linked number it shows all vehicles using that part.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • atxcaratxcar Member Posts: 3
    Thanks for the second opinion. I was lucky enough to find a used control unit from a similar 1992 LeSabre in a nearby salvage yard for $50, ready to go. Swapped it out and the problem is fixed.
  • advent70advent70 Member Posts: 4
    edited August 2011
  • soonerdewsoonerdew Member Posts: 26
    Hi all

    I have 2004 Lesabre Limited with about 89K miles. Has run flawlessly since purchased new. Now experiencing lack of heat in passenger cabin, and noticed recovery tank was low. Refilled to proper fill line, heat returned, but now noticing heat is ebbing again. Believe heater core is clogged. Car engine temp is fine, all running OK otherwise.

    What are the proper steps to get to the hoses to perform a heater core flush? Is a garden hose sufficient?

    Second, if I go to this trouble, should I go ahead and replace the thermostat? If so, does that imply a drain and refill of the system, or can I get by just replacing the thermostat (even if I might spill some coolant along the way)?

    Any other tips/hints appreciate.d
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,727
    edited October 2011
    If you get enough heat part of time, then core is not clogged.

    Pull the dipstick and look at the color of the oil. It should be relatively new looking or dark, depending on how long it was changed. If it looks chocolate like a milky look, there may be coolant getting into the oil due to leaks at the intake manifold gaskets, the EGR tube inside the upper manifold, or the gasket at the throttle body on the end of the upper intake. Coolant in the oil is something to be taken care of quickly, not in a month or so. Coolant in the oil damages the metal of the bearings. The oil with coolant needs to be gotten out and replaced with fresh, even cheap oil, until you get the internal leak fixed.

    Look for drips under the car after it has been driven and well heated and shut off.

    First, with engine cool check the coolant in the radiator. Use the radiator cap to check the level of coolant--not the reservoir. Fill the radiator to the top. Before putting the cap back on, check the underside of the cap for a gooey substance. If there, clean with a small brush and dish detergent, such as a toothbrush. The little disk on the underside of the cap should move free. That's what lets the coolant back into the radiator when it cools, but keeps the pressure in as it heats up.

    Run the car for 10-15 minutes when you go somewhere, then with car parked speed the negine at 2500 rpm for 10 seconds or so, let idle for a few seconds and repeat 4 more times. If you can put the front of car higher than the driver seat on an uphill slope like a driveway that is better. That should get the air out of the heater core according to the service manual.

    Then after car cools check to be sure the radiator level. Fill again if necessary. All this time, keep the level in the coolant in the reservoir between the cold and hot marks.

    Now check the level of coolant in the radiator and the reservoir after several days. If it has gone down again and there are no obvious drips, then look for leaks at the water pump, the plastic elbow at the lower intake manifold to the bracket of the idler pulley for the belt, and at the hose connections. Do this with a flashlight and right after the car has been driven hot and shut down so there's pressure in the radiator so you're more likely to see coolant dripping.

    When the level in the radiator drops a little, air gets into the heater core and less coolant coes through. That means less heat. Often when the engine speeds up, the heat will improve and will drop off at idle.

    There are a couple of other things to ask about, but it's important to establish if you have a leak outside or an inside leak first. Then we can worry about the current coolant.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • atxcaratxcar Member Posts: 3
    Hi Soonerdew, since you topped off your system and the heating worked it indicates that coolant was circulating through the heater core and it is not plugged. Check your level again, most likely it is down again and needs more. If that's the case, your system has a leak in it somewhere and you need to fix it. Check the level in the radiator too, not just the recovery tank.

    If the levels are good, it may now actually be plugged. Two heater hose lines come through the firewall so to flush the heater core disconnect them and use your hose to push water through. If it doesn't go through, it's plugged and you may need to replace the core, which is quite a bit of work.

    Good Luck
  • soonerdewsoonerdew Member Posts: 26
    There are no leaks of any kind on the vehicle. The garage floor (where its parked every night) is bone dry.

    I will top off the radiator as you suggested and see if that affects the heating situation. Just to be clear, the heating isn't intermittent; a partial refil of the reservoir restored the heater to normal condition, but now (about six weeks ago, or so) the hot air temp has dropped again. Your air in the system description sounds apt.

    The manual indicates replacement of the thermostat requires draining the system, but it would seem I could replace it with the engine cold and risk losing/spilling only a relatively small amount of coolant. Does that makes sense? Would be much easier on the wallet to change it myself, and besides I have no faith in nearly any of the local GM dealers not to gouge me with unneeded/extranous repairs.

    Is a true cooling system flush a good idea? I've done it once already with this vehicle a few years ago, around 30-40K miles due to the stories of sludge related to DexCool, but was hesitant a 2nd time as I wasn't convinced a frequent high-pressure flush opposite the normal coolant flow didn't at least risk damaging something.
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