Buick LeSabre Heating / Cooling

keji63 · November 2012

I have a 2003 Buick Lesabre Custom and the fan only works after hitting a bump.
Where is the module located, does it need replacing or is there a short?
Any help is appreciated.
Thanks

imidazol97 · November 2012

fan motor is above passenger's left toes. You can see the round bottom of the motor throught the plastic sound shield under the dash. Tapping this area with your toe will sometimes start the motor again when the key is on.

The motor's brushes may be sticking in the channels, the motor just may not make contact, or the connect from the motor to the hvac box may be corroded from heat damage. You might check the connector after you take off the sound panel.

But 3 screws hold the motor up in place. IT's a medium job because you're lying on your back to reach under and work on it. It's fairly heavy to lift into place and get the 1 inch tube the carries air back to the motor for cooling it in place. But it's doable. Autozone had the replacement motors when I looked for mine.

dmopar · February 2013

I need your help. My 97 buick lesabre has no heat or ac the panel on the dash is completely dead no lights no response when buttons pushed. It is not climate control. I have been on this forum for several days trying to fix the problem. I have no power to the panel. I ran a by pass wire to the blower switch still no results all relays and fuses check good The controller under the dash with the vacuum lines has a 12 volt power wire and when it is plugged in there is about three to four votes that goes to the back of the panel to several wires. What else can it be? Oh I have tried another switch panel same results

imidazol97 · February 2013

Fuse #5A Auto A/C Cruise 15 amp
Fuse #5D Base A/C 25 A
both in driver side fuse block under dash The number tells you the row and column.

the other thing is the one relay for the heater motor could not be pulling in. It's the one with 4 wires. It has two brown wires for low power for the primary coil and the high power ines are brown and Lt Blue.

The other relay for blower has 5 wires because it's a double contact with the primary wires orange and black and high power purple, DK blue, and RED.

The relay pulls in to provide low power to the blower speed switch otherwise there's no contact. I suspect it pulls in when the ON button is pushed for heater or AC.

I suspect this because you do not say anything about the high blower speed working.

This is the relay center

The relays have a tang on the bottom that snaps over a ridge to hold them in plane. Use a long steak knife type device to hold the tang up and they slide forward and out with enough wiring on them to inspect.

The suspect relay is interchangeable with the horn relay or the AC compressor relay. So switch them. I took the cover off one long ago and found the contact was burned on the relay so it wouldn't make contact--this was on the the compressor relay.

The other part is ground. Ground 202 is beside the parking brake area. There's a bolt screwed into the body the way the picture looks.

http://i86.photobucket.com/albums/k110/imidazol97/2012-05-13_195728_bmr1.gif

dmopar · February 2013

Thank-you for your response I switched the relays today, but was not aware of the fuses under the dash I don't have any thing that tells me what they are for. So your info is very helpful.

imidazol97 · February 2013

Note the correct location of Ground #202. I had the wrong ones.

warrriorjoe · February 2013

Heater only working partially and then only when temp at max. Removed glove box and observed temp actuator. It did not move when temp changed. Removed the clip and manually moved blender valve over range and it seemed OK. However, the temp actuator when moved manually (switch off) felt a little "ratchety". When turned switch back on and started car, the temp actuator worked ok until I turned temp down. After responding to the "temp down" situation, and then manually turning temp up, the temp actuator did not move again even tho max temp (just cold air coming out). Did this a number of times with same result. Sometimes tho, the system seemed to work OK. Also, when the temp actuator moves on its on to the full hot position, it makes a creaking sound as it gets near the limit.

Do you think I have a bad temp actuator? Have not checked the vaccuum at this point. I had my brother check GM on part, and they responded with 2 versions depending on VIN. My car is automatic A/C. I do not want to buy part from dealer - can get on-line for less $$$. How do I know what actuator to order (if that is the problem)?

For now, I have removed the link on the actuator and wired the blender valve in the heat position so my wife can have heat (she detests a cold car!).

Also is there any way to replace the actuator without removing the entire dash as the FSM indicates?

Thanks for your advice.

imidazol97 · February 2013

You have the manual control system--it does NOT have the dual temp and digital readout, right? Yours has one actuator on top of the HVAC box?

If I understand what you did, you disconnected the blend door from the electric actuator arm. The blend door moved smoothly. And You wired the blend door in heat position and I assume that gives full normal hot temps when the engine is up to temperature.

My experience is that you should not be able to move the actuator with a gentle force from a finger on the arm. I suspect what you are feeling is the large gear slipping on the axle of the arm. The large white gear cracks and that loosens the grip on the axle. I repaired mine on a dual system by moving the gear so the crack was not in the range of motion and putting superglue between the white gear and shaft (axle). I let it dry overnight. It hasn't failed for a year.

Take out the plastic sound panel under the dash. Take off the 6-7 screws holding the glovebox door on. Then all you have to do (grin) is lie on your back or side and unclip the little set of leads from the actuator to the programmer at the programmer IIRC. The actuator has two screws holding it down. I suggest using fishline or fine string through the socket so it doesn't drop out of reach if it's fumbled. I don't recall the socket size, metric or SAE. This can be replaced without taking the dash face off. Since you don't need the actuator, I suggest taking it out and then finding out what replacement you need...

Try Rockauto.com. You can enter the part number on the actuator and it should give you the updated replacement part number. You can call rockauto/email them if you need more help. I only see two on rockauto--one C67 for manual and CJ2 for auto. Check your trunk tag of options to verify C67. #1571835

The actuator comes apart with a few screws. There are several intermeshed gears and you'll see what I mean. There is a groove on the top with a nub on the axle that limits the travel range.

Good luck on however you choose to attack the problem.

Here's typically what you'll see upon disassembly. There is a lot of gear multiplication, so you should not be able to move the screw gear on the motor by pushing on the external arm... unless you push hard enough to break it. And it probably already has a cracked gear.

Good luck.

riverrat58 · June 2013

I have a 97 Buick LeSabre Limited with dual electronic climate controls. My mechanic tells me the AC Control Head is bad. The unit has a number of names, but it is the in dash display with the push buttons and the digital temperature read-outs that is bad.

My question is, how do I remove the old one, and install a new one? I found a replacement part in a on-line junkyard, but have no idea what steps to take to remove the old and install the new.

goodvibez · June 2013

I have a similar question. A friend came to me and said she has a 97 lesabre and a mechanic told her the blower module is bad. She doesn't have any fan on heat or ac settings. The display lights up and you can go from 60-80degrees. Is this a easy fix and where Is it located?

imidazol97 · June 2013

The removal for the radio/HVAC control is that the plastic wood pieces pull out of the dash with metal pressure fittings. Just give a good pull.

Then the front of the dash comes off with a screw in each of the air vent openings at the bottom after you remove the movable air deflectors. Do not drop the screws down the air openings. This is called the trim panel. My 98 FSM only shows the 4 screws holding it. There are either more screws under or there are press fit friction clips.

I am not sure this is a good set of instructions. I have never had that panel off on my car.

I also think that usually the problem with the controls is the programmer box under the dash on teh corner of the heater box or one of the two electrical fuses.

imidazol97 · June 2013

>the blower module is bad

Was that the blower control module? It's the equivalent of the resistors that change speeds in the regular control setup.

the Blower Control Module is where the power cables from the blower motor lead up on top of the heater duct the motor sits in. The module is cooled by the air just like the resistors are.

If it's bad, there is no fan, but everything else works okay.

The relay center above it is held by two screws and can be lifted slightly to give access room to the two screws holding the module in.

Remove the negative battery cable before moving the relay center with its fuses and relays.

stresd_damzel2 · June 2013

My 2002 lesabre has starting overheating on me. The first time my mechanic said it was this tube that runs through the engine block. He said if that is rusted inside it will make it overheat so he changed the external tube and it stayed normal for like two weeks. So then it would only overheat when sitting too long ar a light vut as soon as i drive itll drop a few noches, not completley but out of danger. So, i changed thermostats, hoses, put only coolant and it worked for like a week, temperature stayed below danger but above normal. Now it completley overheats to the point where the car has cut off. Is my problem the waterpump? there is no water leaking. HELP! 

imidazol97 · June 2013

Take a look at the color of the engine oil on the dipstick. If it's a brown, milkshake color, your coolant may be getting into the engine oil. That's fatal if it has gone on for a while.

I don't understand what the mechanic did. But the most common problem will be the gasket under the metal lower intake manifold and the heads has deteriorated and is allowing a leak into the engine air intake and the oil pan. That may explain the stalling because the coolant causes misfiring in the cylinders.

A second problem area might be the intake manifold that's plastic where it meets with the metal throttle body that controls the air intake and volume. That gasket can leak.

A third area might be the EGR internal port which is hard plastic has deteriorated with heat--not as likely after 1999.

A fourth problem might be not the above but that the coolant is goopy if someone added regular green antifreeze to the original orange DexCool. That may be blocking some of the coolant flow through the radiator.

You need to find a good mechanic who knows these cars. A dealer may be your best bet for an analysis of what the problem is, despite their higher cost. You may be spending money as well as time with damage occurring at a poor local mechanic.

shildebr · July 2013

Is there a chqnce you still have these pictures and how u fixed this issue. This is the exact issue i am having with my 1999 buick lesabre. Thanks for ur help.

lmcclenton · July 2013

I had to replace my battery and now my ac is not working. Air will only blow through the defroster and it doesn't get very cold. I have had my car looked at and was told that my a/c unit is working fine and it is probably an actuator but now sure how to decide which actuator to buy. I have automatic ac with temperature display but not dual controls. Please help...

imidazol97 · July 2013

What year is your leSabre?

When there is no vacuum, the system should go to defroster for safety.

But on 1999 and prior, there also is a problem with operation of the actuator for the door that blocks the defroster and makes air come out the dash vent.

bhopp · August 2013

2002 lesaber heat blows cold unless temp set at max 90 it is a limited w/dual control

bhopp · August 2013

where is temp sensor for heating system dual control digital system

eagleman60 · September 2013

My 99 Buick Lesabre AC doesn't blow through vents. It only blows out the defrost and floor. It works on all fan speeds. No matter what air flow position I select on the Ac head unit it will only blow out the defrost and floor. I have done a lot of reading on this problem and thought several times I was close to solving the problem with disappointing results. Here is what I have done to this point. I have replaced the AC head unit twice, what they call the Air Mix Actuator and the AC programmer. (All parts from local salvage yard). The vacuum line leading in from the fire wall has been vacuum tested. When I first turn my key on the 2 levers of the doors move to the right and then back to the left. If I change my temperature on the head unit to warm then the 2 levers move to the right and I have heat. So I am assuming the doors are functioning properly(??) But like I said no matter what air flow selection I choose on the AC head unit I only get air flow from the defrost and floor. Nothing comes out the vents. I am at a loss. Can someone please help? FYI... I had the same problem on a 94 Lesabre and I change the head unit and the problem was solved for about a year. Then it would from time to time just blow out the defrost and floor. You could just be driving down the road and it would switch back to the vents. Makes me wonder if the head unit was the whole culprit on the 94 or not? I've sold the 94 so it is not an issue now. I thought I would mention my 94 problem just so you know my frustration with Lesabre AC issues. Once again CAN someone please help me?

imidazol97 · September 2013

If the other vacuum controls move correctly when set on floor/windshield, and you are sure you have correct vacuum with no leaks at the storage tank behind the headlight, and you can move a line off the floor control diaphragm on the driver side and put it on the diaphragm for the upper doors (blue line), then you have a problem with this sucking shut.

http://i86.photobucket.com/albums/k110/imidazol97/DSC03124.jpg

You can cut it off from the vacuum lines and slide vacuum line over the tubes (Oreilly's sells it by the foot or in boxes). Connect the correct color from the inner part of the programmer box to the color on the outside--they are not all the same.

Programmer sits on corner of heater box.

http://i86.photobucket.com/albums/k110/imidazol97/HeaterCore1-1.jpg

You can reach all this by removing the sound shield under the dash and removing the glovebox door at the hinge.

grizzlymanbear · November 2013

i have 97 buick lesabre. last winter, the heater worked awesome, not a problem. so far this winter, the heater blows cold air, even after letting the car run for 10-15 minutes. the airflow will start going to warm after driving it for a little bit, but not much (in a 30mph zone). hopping on the freeway, the heater works just fine, but when sitting at a stop sign, or a stop light, it starts blowing cold again. any ideas?

imidazol97 · November 2013

I assume it's the manual control heater and the actuator for the temperature is working right. See last paragraph.

Your car may have a thermostat that is not closing completely when cold or opening too early. After 5 minutes with a cold engine, the upper hose should still be cold while the heater hoses are warm and hot. You should be able to feel the thermostat open when the coolant gets to 195 as shown on the dash gauge, by the hot water coming into the upper hose in slow spurts and warming it some. The thermostat may open slowly and just the bottom of the hose gets warm at first. After 10 minutes or so, the upper hose should be too hot to hold for more than a few seconds unless your hands are really toughened up from being used to hot things.

You might have low coolant level in the radiator--have to take the cap off when cool to see if there is coolant up to the cap level. Can NOT check just the level in the plastic reservoir. But that usually has a couple other symptoms.

Your coolant may be old and clogging the heater core lowering the flow rate. If you are careful you can check the temperature of the two lines into the firewall behind the engine. Be careful of the moving belt at the alternator. After the engine and car have been warmed up, with the heater blower on high the temperature of the one metal tube should be some cooler than the other one. But both should be hot. If you turn the fan speed on low and retest, the tubes should be nearer in temp due to the water in the heater core not being cooled as much by the air.

Having someone run the engine at 1500 rpm or more for a minute before testing should improve the temperature of the out hose making it closer to the input temperature.

If the flow in the radiator is partly blocked, you can have the cooling system cleaned with a cleaner to try to pick up some of the gunk in the heater. The better solution is to take off the rubber tubes at the engine end and try to flush the heater core with light water pressure in both directions.

A remote possibility is a water pump.

The electric actuator on top of the heater box pushes a white plastic arm and a metal rod to move the temperature blend door. That actuator may be slipping and not pushing the rod all the way to the hot side. You can take off 3 screws and a couple taps on the firewall to remove the plastic panel under the dash. Take off the glovebox door for easier access--7 screws across the bottom hinge. You can try to move the actuator with a gentle push. If it moves, the inside axle is slipping due to a cracked gear. OR you can watch it move as you change the temp setting with the key ON to see which way it goes for HOT, and then try to push it further and see if you get more heater with the engine running in that position. If the actuator is going full hot, with a hot engine running at 40 or more the air coming out the vents should be so hot you can't hold your hands there.

jdunaway · January 2014

Hello. First let me say what you are providing is awesome !! I have read many of your posts and the answers are intelligent and insightful. So I am hopeful you can help me locate my problem. My friend has a 95 Buick Lasbre. Complained of low heat. I know a little about a lot and I love to help so here I am lol. I noticed the coolant looked rough and she said she can't remember it ever being changed. So that's the first thing I decided to do. Never over-heated and all of the manual controls worked well so I figured it was a good start. After flushing and draining 3 times I added Prestone's mix and let it warm up. Had awesome heat. On the drive back to her house it all dropped out and went right back to blowing cold air. I opened the hood and felt the upper radiator hose. Slightly warm but nowhere near what it should be. I noticed both fans were running. I let it sit and idle for about 15 mins and the air was still cold. Fans still running. Hoses still cold. I didn't think to reach back and feel the heater hose lines. It is 6 degrees out there and night time. Should those fans be running when the water temp isn't hot ? It only has a temp light so I do not know what the engine temp was Tomorrow I will dive deeper. Any advice would be awesome. BTW, sliding the cold/hot slider works well, switching from defrost to floor, to blend works well.

imidazol97 · January 2014

@jdunaway said:

I opened the hood and felt the upper radiator hose. Slightly warm but nowhere near what it should be. I noticed both fans were running. I let it sit and idle for about 15 mins and the air was still cold. Fans still running. Hoses still cold. I didn't think to reach back and feel the heater hose lines. It is 6 degrees out there and night time. Should those fans be running when the water temp isn't hot ? It only has a temp light so I do not know what the engine temp was :

Check the coolant level in the radiator--not the reservoir--tomorrow. You may not have gotten all the air out. Fill radiator with coolant with engine running. Then rev engine, either yourself with the throttle on the engine or have someone hold it at 1500 or so and add coolant then put on cap while revving. Drive car until it should be fully warm. The fans should not be running. I suspect you were running hot. They may come on at 217 or so. With 6 deg outside, it was easy for the low coolant to keep below emergency temperature.

After upper radiator hose is hot with coolant leaving engine through thermostat, run engine at 2500 for 10 sec or so then idle. Repeat 4 times. That should move air out of heater core. Then last open the little screw on top of the thermostat housing on upper radiator hose on engine to let out the air. You can do this with engine off while still hot. Open screw until air bubbles out and you get coolant.

Did you replace the thermostat? Should have done that as prevention. They are good for a limited number of cycles; then you are riding on borrowed time. I recommend Stant Superstat at 7.99 at advance auto parts and a new rubber o-ring that slips over the metal edge of the thermostat for 3.50 or so. If you are going to do the thermostat, drain out about a gallon of coolant before taking off the thermostat housing.

After flushing and draining 3 times I added Prestone's mix and let it warm up.

If you rinsed with plain water and then added 50/50 Prestone, you do not have enough antifreeze, in my opinion. The volume is about 13 quarts for the system. If you're rinsed and drained 3 times, you have little left of the original coolants. If you added 50/50 Prestone that's not 7 quarts of Prestone. Each gallon on had 2 quarts of pure Prestone.

Did you open the drain on the bottom of the radiator? That may have drained more plain water out. My method was to rinse and drain after warm up, 2 or 3 times. Then add the 7 quarts. Then add more water if needed. That way I knew the 6-7 quarts was in there for freeze protection.

Get a gauge that measures the antifreeze temperature--even if just one of the little floating ball devices.

jdunaway · January 2014

I'll be replacing the thermostat later today. Like you said, I figured it's a good thing to do and easy so might as well. I did remove the lower radiator hose and drained that way. The petcock always seems to be a problem so I didn't even bother with it. I have already did as you described by running the engine up to 2500 and then idle 4 times and removed air via the set screw on the thermostat housing. I had awesome heat for around 30 mins or so while it was idling in the garage. When I took it for a drive is when the heat went suddenly cold and never returned. The top radiator hose was barely warm and those fans wouldn't shut off. Is it possible that the thermo switch for the fans gets stuck on ?

imidazol97 · January 2014

@jdunaway said: Is it possible that the thermo switch for the fans gets stuck on ?

When you start the engine cold are the fans on? That would be true with a stuck relay.
I don't suppose you have a scanner for the cars that's more than a code scanner: I have a
scanner that shows the engine temperature that the computer is seeing.

I had awesome heat for around 30 mins or so while it was idling in the garage. When I took it for a drive is when the heat went suddenly cold and never returned.

That sounds like air in the heater again. What's the coolant level in radiator? If it dropped again you may have gaskets leaking coolant. That's a Series I engine though, isn't it.
Or you have a glob of something that moved and blocked the heater core. See what happens after thermostat replacement. And do testing after idling to warm up of heater hoses. Also check that the thermostat starts releasing hot water after getting up to temp; you'll feel the bottom of upper hose get warm first as a little coolant is released. Then more until the whole hose is hot.

The top radiator hose was barely warm and those fans wouldn't shut off.

Are you in a climate where the air temp gets above 45-50 deg? And you have the HVAC controls set on something where the AC is turned on automatically--turn on the Vent button and see if fans turn off after a minute.

jdunaway · January 2014

It's around 10 degrees outside now. Last night it was 6 and the fans were on during idle while the radiator hoses were cold. I'm not sure if they were on while it was cold and a fresh start up. I'm gonna go get the car now and run some more tests. Also replace the thermostat. I'll burp the system again and add fluid while revving the engine up. I'll also check the heater core hoses after it gets hot and see what I find. I'll report back in a few hours. Thank you for your responses !!

jdunaway · January 2014

Well I cleaned the relay connections, burped the system, new thermostat and gasket, and filled the system while holding it at 2000 rpm. All seems well.

gregory20 · February 2014

Needing some help for my 1995 Buick Lesabre. When turning on my heater or AC I can hear the blower motor running at all of the different speeds (I have the manual control with slide lever) including high speed but I hardly have any air coming out of the vents. I can switch between defrost, vent, floor and the air is redirecting where it should go and is very warm since it's cold outside, but there is hardly any airflow. I turn on the recirculate and still only have minimal airflow out of the vents when in high position. Have replaced blower motor and tried a different electronic control module inside the car; took apart the vents on outside of the car to make sure they weren't plugged; have used my DMM to make sure all fuses are good and that I have voltage. Not sure what else to try. This problem occurred literally overnight the airflow was fine one day and not the next. Any help is appreciated.

imidazol97 · February 2014

@gregory20 said:

When turning on my heater or AC I can hear the blower motor running at all of the different speeds (I have the manual control with slide lever) including high speed but I hardly have any air coming out of the vents.

As I read this it did NOT happen when you replaced the blower motor? I have read of one where the blower motor was turning in reverse. Also some have had the squirrel cage loose on the axle so the motor was turning but the squirrel cage was not.

Disconnect battery negative.

If you are able to do this yourself, I suggest looking into the resistor opening. It is on top of the blower motor box area. The power lead from the blower motor goes to the resistor. The relay center above that is held by 2 screws and these can be removed leaving the relay center loose. It can be moved up to give better access to the two screws holding the resistor into the heater blower box area.

If you can hear lots of air sound as the blower runs on high, that is a good sign. I'd try reconnecting battery and running blower motor to see if a lot, lot of air is coming up out of resistor opening because the other flow path is restricted.

Once that is open, you can see the front of the AC evaporator. People have found these covered with small grass or straw material and with dirt and oily mixtures from years of air with road dust in it. If you see oily material, people have recommended Gumout carburetor cleaner. If you need, I'll try to find a source for that. The AC evaporator has a drain for the water, but this must be done slowly to allow water to drain. Put plastic under heater box inside car with towels on top to catch any water that gets in there. Gumout sits for a while and then you can use a garden pesticide pump sprayer to spray water on it to rinse. Or a well-controlled garden hose.

You may have a problem with air through the various mode valves. But if AC is open, then you might have a blocked heater core. That would require taking off the door to it inside the car. It's two screws, lots of sealer, and two hooks at the back end if I recall the pictures. But not easy. Can be done without removing dash. Maybe the glove box can be removed for better access. Requires lying upside down on seat and shoulders on floor.

Before going after heater core for inspection, I'd verify the blower motor and AC core are both working right. You've replace blower motor AFTER this occurred, so that's odd. I would suspect a broken mode door but you say you are able to direct air everywhere with vacuum controls. I would suspect a broken actuator or door for the blend. You can watch the blend actuator, electric, sitting on top of the heater box as you move the temperature slide. Those actuators crack a gear inside which is press-fitted to the axle. And the axle slips as it's being twisted to move the link to the blend door. A test is whether the you can change temperature from very hot to very cold with that electric actuator.

Just for my interest, when the heater is blowing on high and set on floor, how much air is coming out the defroster? There should be very little bleeding to the windshield--just enough to keep it clear from slight fogging without having to switch to heat/windshield where you would get more flow to the windshield.

2buicks · April 2015

Hi, I replaced the battery on my wife's 2002 Buick Lesabre Limited and since then, the AUTO button engaged on the climate controls will not engage the blower motor when starting. I did verify the compress is engaged when the blower does not come on. In order to get the blower to come on, I have to press the off button and then press the AUTO button and the blower comes on normally. Prior to me changing the battery, we left the AUTO button in the on position all the time and never had to press anything other than to occasionally change temps.

My question is, does the car have to go thru a "relearn" process of start/runs to get this function back to the way it was?
Any suggestions would be greatly appreciated. Thanks - Rick

imidazol97 · April 2015

2buicks said:
Hi, I replaced the battery on my wife's 2002 Buick Lesabre Limited and since then, the AUTO button engaged on the climate controls will not engage the blower motor when starting. I did verify the compress is engaged when the blower does not come on. In order to get the blower to come on, I have to press the off button and then press the AUTO button and the blower comes on normally. Prior to me changing the battery, we left the AUTO button in the on position all the time and never had to press anything other than to occasionally change temps.

My question is, does the car have to go thru a "relearn" process of start/runs to get this function back to the way it was?
Any suggestions would be greatly appreciated. Thanks - Rick

What happens when you push the faster/slower switch for the blower, which
takes it out of automatic control? Does the blower come on?

Don't know about a relearn procedure. However, the blower motors do fail
with the brushes not making good contact. To test, take your toe of your left
foot up against the bottom of the heater while sitting in the passenger seat. Tapping
slightly often vibrates the motor and causes the brushes to make contact again.

So with the key ON and the controls set and the motor seeming to not react,
vibrate the blower motor itself. You can lie on the floor on the passenger side
and see a round area cut out in the plastic dust shield which is the blower motor.
You can manually bump that or tap it with your toe.

Blower motors are replaceable.

2buicks · April 2015

Imidazol97- Thanks for replying. Everything works. I can hit the fan blower speed button which takes it out of AUTO and it works fine. In fact if I leave it there and turn off the car, when restarting the fan motor immediately comes on. Like I said everything works fine, but it seems the car will not remember the car was in the AUTO position the last time it was turned off. We then have to press the OFF button, then press the AUTO button and then the blower and A/C comes back to normal. A bit of inconvenience, but I am just worried about the additional stop and restarts of the compressor when having to press the off button and pressing the AUTO button. I have not checked the fuses, but what does the #37 HVAC BAT fuse do?

Oh, and by the way, the blower motor has been replaced within the year and has not been a problem until just now with replacing the battery. A little puzzled here, do you think disconnecting the battery and reconnecting will reset what has gone wrong? Thanks for any help you might have! - Rick

imidazol97 · April 2015

2buicks said:
I have not checked the fuses, but what does the #37 HVAC BAT fuse do?

Now that the most common thing is off the table..., I'd guess you've got a fuse out. I believe there are two fuses serving the programmer (the brain). One supplies normal power (#33) and the other is always connected and retains the memory (#37). Your owner manual should indicate both fuses and location. I have a factory service manual to dig out if that doesn't discover a dead fuse when you check to see if your symptom is listed in the troubleshooting.

thecardoc3 · April 2015

All of the diagnostics with this system require the use of a scan tool that supports it. There is a recalibration function that can be performed with the scan tool as well, and while the system should do that automatically if the system loses power (battery disconnect) a failure \in the system will cause that to not complete and you end up right back at needing a scan tool to proceed.

2buicks · April 2015

Thanks Imidazol97 and Thecardoc3 for your replies. Haven't had a chance to look at it today. Had roofers here replacing a section of roof in between rain showers!

When I went thru my owners manual and saw the #37 fuse, I thought that might be the culprit. Let's hope anyway. It's very frustrating because everything else is working. The car just can't remember the AUTO button was in when it was shut down!

Thanks guys, I will leave another comment when I have a chance to check the fuses.

imidazol97 · April 2015

2buicks said:
When I went thru my owners manual and saw the #37 fuse, I thought that might be the culprit. Let's hope anyway. It's very frustrating because everything else is working. The car just can't remember the AUTO button was in when it was shut down!

What happens if you leave the settings manually chosen? E.g., fan speed 3, temp at 80, and floor only for heat? Does it start back up after shutdown in those same settings?

I haven't checked the factory service manual, but I'm wondering if those settings are remembered in a body control module that remembers the seat and mirror settings for the two drivers plus the exit setting?

The local car technician who had a radio call in program talked about disconnecting the battery and holding the positive and negative cables together to drain power stored in capacitors from the modules that remember settings. If you don't find a fuse blown, that might be your next step. It may not make a diffrence, but I'd put the HVAC controls in OFF before shutting off the ignition. Then remove the battery cable and lay it against the positive at the battery. AND leave it off for a long time such as a half hour. Then reconnect. Turn key to ON and wait while things reset. Then start the engine. Then hope it might have cleared you problem.

2buicks · April 2015

Imidazol97 - I just checked #37 fuse and it is not blown. I disconnected the negative post for 30 seconds, reconnected and it is the same. Yes, I can have the system in manual cool and turn off the car, when I restart, the blower, compressor all comes back without touching a thing. It's only the AUTO button engaged that it is not remembering. Oh, and I did reprogram the comfort settings on the door, each driver when all this started and that did not help with the AUTO. I wonder if the scan tool that THECARDOC3 mentioned could clear this. My A/C man might have one, I just hate going to the Buick dealership, it's always major CHA-CHING with those folks!

2buicks · April 2015

I have to put the back seat in for right now, my wife has to use the car. She is fine with having to turn off and then press the AUTO, but I am concern with all the extra turning off and turning on of the compressor. What are you thoughts?

thecardoc3 · April 2015

The compressor turns on and off all of the time anyway, so that isn't any concern.

2buicks · April 2015

Okay, I just didn't want to put any additional strain on kicking it off and then kicking it back in, but you are right, it does cycle on and off anyway. This is really got me baffled. At least the air still works, it's just that AUTO button doesn't stay engaged! Thanks for your replies! - Rick

imidazol97 · April 2015

2buicks said:
I have to put the back seat in for right now, my wife has to use the car. She is fine with having to turn off and then press the AUTO, but I am concern with all the extra turning off and turning on of the compressor. What are you thoughts?

Did you leave the battery disconnected for 30 minutes? Did you connect the positive to the negative while off to discharge the system?

I looked in the factory manual and it's vague about the logic and operation of the HVAC. I does not have a troubleshooting segment for the Auto setting not remembering blower.

Out of curiosity, what happens if instead of turning the control OFF, you just use the blower speed rocker switch to change the blower speed?

As for working harder to get this repaired, I'd just live with it. I am especially interested in whether the system takes over the blower again when it fails in Auto by going to manual settings. The compressor gets turned on and off with the car's engine or with changes in the controls. But otherwise it's always on as a variable compressor.

There are some other things that go through my mind. I assume you are in AC mode? If in heat mode, the program might be waiting for the sensor to indicate the coolant is warm enough to have the blower start on to provide heat. A bad sensor might not be giving the hot coolant reading. But your problem came after disconnecting the battery and probably the HVAC control was left ON when you did that.

If in AC mode, I believe there's a purge setting where the system uses a higher rate of flow for the air to help get hot air out of the car.

2buicks · April 2015

Imidazol - No I didn't hold the positive terminal to the negative terminal as I had disconnected and reconnected the battery at the negative side before I read your post. Oh, and prior to replacing the battery I did have the A/C turned OFF. I have two Buicks and I read somewhere after I bought my '97 Lesabre that it is advisable to turn of the A/C prior to disconnecting the battery. Yes, I think I will live with it like this. I am going to get with my A/C guy and see if he has a GM scan tool. The Cardoc3 said the scan tool can scan and recalibrate the system. New technology, you and Cardoc3 know more about the newer systems than I could ever hope for. Maybe a relearn will happen yet, who knows? Thanks all, I will leave a comment when I have any updates! - Rick

imidazol97 · April 2015

I received this question from gerald22 about a problem with inoperative controls for the HVAC on the dash:

gerald22 → imidazol97
The 1993 Heater/AC controls do not light up, buttons are not active. Replaced the control with a known working unit, and still is not active, seems like not receiving power, however the blower fan runs on high all the time the key is turned on.

imidazol97 · April 2015

Is anything else not working? Have you checked fuses for the HVAC? There may be more than one.

The first thing to check would be the ground IF you can verify there is power on both fuses with the key ON.

The ground bundles that are under the door sill on each side sometimes had trouble with corrosion due to moisture carried by the shoes into the carpet. I do not know which side the ground for the programmer box and the controls use.

I do know that my 93 would lose the power door locks AND the HVAC came on with the compressor working and in default mode which is defrost and high fan speed. So I suspect you have a problem ground buss.

You
If you know how to use a voltmeter, check the ground wire from the control.

These show the location of the ground buss on the driver side. There's also one on the passenger side but
I don't know that it's related.

http://i86.photobucket.com/albums/k110/imidazol97/DSC00977.jpg

http://i86.photobucket.com/albums/k110/imidazol97/connector.jpg

http://i86.photobucket.com/albums/k110/imidazol97/connector2.jpg

http://i86.photobucket.com/albums/k110/imidazol97/100_1929.jpg

thecardoc3 · April 2015

That system ran on what is known today as a LIN bus communication network. (Local Interconnected Network) and it could be accessed with a full function scan tool that communicated on pin J of the ALDL. The network was called E&C which stood for Entertainment and Control. It's notable that a number of the cars that had the E&C bus usually had the communication pin removed from the diagnostic connector and the technician had to access it and install it into the connector during testing, and then once done remove it from the connector and tape it back into it's rest position.

The control head not lighting up would have a tech first needing to confirm power on pins 12 Brown from the ignition switch and 13 Orange from battery positive. Based on the O.P's description and the fact that he isn't reporting a drivability issue such as a stall or random no start the ground bus is actually unlikely to be causing his vehicle issue. When the ground bus you identified is failing it typically also shuts down the fuel pump and other systems like the power seats, power windows. Since he is only losing one system a better approach is to start all of the testing at the control head connector. If the ground circuit is in fact failing, it could be proven by measuring the voltage drop across it at pin 1 black/white to a known good ground. (battery negative if possible)

While widely accepted as necessary, touching the battery cables together to help discharge capacitors in the system really isn't necessary nor advisable. Any system that doesn't use a control module or other switching device in its primary control if operated easily drains the caps as well. Things like brake lights, dome lights, if operated not only make a connection from the battery power to ground for you, they have the added safety concern of bleeding the power off across at least some resistance which helps protect a module from a sudden current surge that could occur when the cables are grounded together to attempt a discharge.

2buicks · April 2015

2buicks said:
Imidazol - No I didn't hold the positive terminal to the negative terminal as I had disconnected and reconnected the battery at the negative side before I read your post. Oh, and prior to replacing the battery I did have the A/C turned OFF. I have two Buicks and I read somewhere after I bought my '97 Lesabre that it is advisable to turn of the A/C prior to disconnecting the battery. Yes, I think I will live with it like this. I am going to get with my A/C guy and see if he has a GM scan tool. The Cardoc3 said the scan tool can scan and recalibrate the system. New technology, you and Cardoc3 know more about the newer systems than I could ever hope for. Maybe a relearn will happen yet, who knows? Thanks all, I will leave a comment when I have any updates! - Rick

Had my A/C man scan the system with his Snap On scanner and he did get an error message that a motor was stuck in the cool mode and he couldn't clear this without physically getting to this device. He said most of the dash would have to come out and it would end up costing around $700 to get my AUTO to start remembering last position at shutdown. I have given up on it. Thanks to both you and Cardoc3 for your suggestions. Sometimes the "EASY" works, other times "it ain't going to happen!" - Rick

huntswnm · May 2015

Well I have read through all 10 pages of questions and comments, and have one of my own. 1997 with push button controls and manual slide temperature selector. Upon acceleration the A/C will go from vents to defrost vents. I know that it has something to do with a vacuum leak somewhere, I am just not sure where to start looking. Thanks for any help!

imidazol97 · May 2015

huntswnm said:
Well I have read through all 10 pages of questions and comments, and have one of my own. 1997 with push button controls and manual slide temperature selector. Upon acceleration the A/C will go from vents to defrost vents. I know that it has something to do with a vacuum leak somewhere, I am just not sure where to start looking. Thanks for any help!

How good are you working under the hood?
It's likely to be a vacuum leak as you said. Most likely,
it's under the hood. You might have a vacuum leak in a diaphragm
that's under the dash--there are 4, IIRC, that pull the various
doors in the HVAC to make the air go where the dash control asks.

Under the hood, the engine cover comes off. Unscrew the oil filler
TUBE, not just the cap. A quarter turn and it pulls up, and the gray
engine cover comes off. On the right rear, facing the car, there's a large
black tube to the 12 inch diameter brake assist on the firewall: next to
that tube at the engine is a small black plastic tube that supplies vacuum
to the interior.

That black plastic is probably okay there. It goes into a bundle with electrical
wires and goes to the passenger side. Take the thin plastic cover off
the Relay Center on the firewall (2 small twist catches hold it IIRC)
and you can see the black plastic tube at the passenger side. There will
be a one-way valve in it. Try to gently twist the tubes off the end--
REMEMBER which end goes toward the engine. Try sucking air
through that valve: it should only go one way which is toward the
engine side. Those valves occasionally allow air from
the engine to the HVAC system side ,
when the throttle is opened. That lower
vacuum lets the diaphragms relax which puts the system in failure
mode for safety which is defrost air flow.

Next to the one-way valve is a T" connector. From the T vacuum
goes to the front under the headlight area in front of the wheel
There's a plastic container which "holds" vacuum. (Lie on ground
and look up in front of the wheel. Those tanks can crack.
That lets air in and makes the system more susceptible to dropping
vacuum from the engine. A test can be to get the connector off for
the tube. Then replace and start the engine. Have someone turn engine
off and wait a few seconds listening for air sucked into that tank
through a crack. Remove that connector and you should get a rush
of air into the tank.

Good luck. I feel this is the area where your problem might be.
There are other things you should check if you are able to
check on the engine. I might be able to find sketches of the
parts. I used to have photos of the T-valve but I am not sure
they are still in my photobucket account.

EDIT--photo of one-way valve. Note the rubber instead of
plastic tubing there. Check that rubber for deterioration or
leaks due to heat and age. To the left is the T connector where
one end goes to the storage container and other goes
inside the car next to the A-pillar area below the dash.

http://i86.photobucket.com/albums/k110/imidazol97/DSC04726.jpg

Buick LeSabre Heating / Cooling

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