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Pontiac Bonneville Heating/Cooling Problems

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  • Clean Evap core, replace Blower and resistor. All the settings work(from defrost to vents to floor)
  • phr04phr04 Posts: 1
    The instructions for replacing this motor seem to indicate that it can be reached by removing the instrument panel cluster. I have done that and am still a long way from even being able to see the actuator. It appears that the entire dash panel assembly, including the air ducts must be removed. Is this true, and can I find step-by-step instructions for doing this?

    PHR004
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,045
    edited October 2011
    > It appears that the entire dash panel assembly, including the air ducts must be removed.

    No. It can be done by removing the underdash hush panel (thin plastic) and taking off the glovebox door.

    If you want to email my email given in my profile (click on my user name at top of this post), I'll try to link you up with some help.

    The Bonneville has a different dash structure in that area than the leSabres. Yours is harder to get to.

    First, you need to verify that the electric actuator is not moving correctly, by looking through the hole in the brace behind the glovebox where you can see the rod that the actuator uses to move the door. If you find the actuator is bad, it can be removed by taking off two short screws--but they do it by feel since they're next to impossible to see.

    What happens is the actuators have a plastic gear inside that splits so it's not pressed against the hub and slips. The hub is what moves the actuator rod.

    I removed mine and glued the gear to the actuator. But mine is easier to replace if it breaks or slips again. So I decided I might not own the car by the time it comes loose from the plastic instant glue.
  • ac82ac82 Posts: 1
    I am in the process of replacing the blend door actuator on my 98 Bonneville. I can not access anything behind the glove box so I removed the cover off the blend door / A/C coil box to get to the actuator motor...Now I can't get it to go back under the dash...It came out so I know it has to go back in! I am at my wit's end. I would appreciate any help!
  • I'am having problem removing the programmer. I have removed the cover under the programmer, and the glove box, and can't seem to get any futher. I see the tubes going into the box, but now I still can't remove it.
  • I have a 1998 sse Boniville the blower motor would quit intermeditley now it quit working. I check the motor by running wires from the battery and it works great. Controls inside the car show the blower on any speed but nothing i have checked all fuses I show about 9.5 volts in the wires going to the motor. I have digital controlls. is that enough voltage? I don't know where the blower motor control mod is? or if that is even the problem or if the voltage is to low. I do know that there are three computers that control that system. Any help would be great as it is the wifes ride and I'm in the dog house untill i get it fixed.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,045
    edited March 2012
    image

    image

    The location is where shown. Follow the wires from the blower motor up. The relay center above the blower control module is held by two screws. Remove those and it can be pushed upward with slack on the wires and give some room to get the BCM out of the airbox.

    The module is electronic. They will show voltage but no current. If the blower runs when connected directly to the battery on a fused line and with a ground, then you're probably needing the BCM for roughly $100? Available at Rockauto.com and other local box stores.

    If you do not have the digital speed control on the blower, then the same location would have a resistor set that gives three speeds.

    The only other possible problem is burnt contacts on the connections due to high heat. So take a look.
  • Trying to figure out what could possibly be wrong with my wifes car. When the A/C is on the cool air blows out from the floor vents just fine ( I think ). When you push the button to go to the vents on the dash board, the air coming out of the vents on the passenger side comes out cool but on the driver side there is a noticeable (hotter) difference. Does anyone have any idea what could be causing this. I thought it might be the blend door actuator, but the air itself is being diverted correctly, the only problem is the temperature of the air on the drivers side vents on the dash when it is on A/C. Any help that anyone can provide will help out immeasurably.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,045
    edited March 2012
    You are dealing with three separate electric actuators.
    .
    One controls the direction of airflow for both systems, driver and passenger sides. That is not a problem since you can change the air flow path which is the same for both sides.

    One controls the air temperature blend door on the driver side.

    One controls the air temperature blend door for the passenger side.

    By removing the underdash plastic cover carefully, you can then watch the movement of each of these by the white center rotor on the electric actuator while you change the temperature demand on the dash with the key ON (I don't think the engine has to be running).

    I suspect you'll find the driver side is not moving all the way through the range of motion.
  • First thank you for all the great information.. I lost my highest fan speed and I looked at the illustration above but I cant tell if I replace the fan motor from under the hood or under the dash, can you please point me in the right direction on what I need to do Thanks WM
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,045
    Why would you replace the blower motor? If it runs on the 3 lower speeds, that means the fan motor is okay.

    Notice there is a separate circuit for the highest speed due to the high current draw. IIRC it has its own fuse in the relay center under the hood. AND it has its own relay. Either of those may have failed. The relay is in the relay center under the hood.

    If you are able to do some electric troubleshooting, test for power on the purple line to the blower motor when the fan switch is on HIGH and the key is ON. You probably are getting 12 volts on the other 3 speeds and then when you switch to HIGH, the voltage drops to zero.

    The cover for the relay center comes off easily. I do not know if there is a diagram in it showing which large fuse goes to which circuit. You may have to test each of them for 12 volts on both poles.
  • Thanks for the help I can definately do a voltage test to the blower motor,,Is the motor under the dash or under the hood? Or should I just check it at switch?? Thanks again WM
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,045
    Blower motor is on the firewall center behind the engine. It has a round cover with 5-7 screws holding it in. Follow the leads from the motor up to the top of the air passage that carries the air from the blwoer motor.
  • Thank you again it was the fuse and its working. Now Im having trouble with the engine shutting off intermitent. I think it may be the ignition switch because I can wiggle it and it will come back on. How does the switch come out, do I have to pull the steering wheel or is there an easy way to change it,,thank you again . I'm a motorcycle mechanic and working on cars tends to make me crazy
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,045
    edited April 2012
    The ignition switch itself is on the top of the steering column under the dash. It's linked to the lock cylinder at the top by some kind of rod. Many people think it's up at the top with the lock cylinder.

    Several H-body posters have had problems with the switch. Check rockauto.com for it and look for a 5% discount code that goes into the "where did you hear about us" box.

    To replace must not be terribly difficult from what folks in Pontiac forums have said. That's as long as you can get your body in there between the door frame and the seat or lie upside down on the seat and hang over down onto the floor. I worked under there on the diaphragms for the HVAC control valves, but I didn't check on how the ignition switch looked.

    Part #80
    I suspect you need to disable the air bags to do this.

    image
  • Hi,
    I have a 96 Bonneville and got the a/c fixed a few summers ago and then it went out again the next summer. I don’t want to dump a ton of money into it but it allows heat in on the floor board all the time. When i turn the blower on i can switch between floor, vent, and defrost, but when everything is off heat pores in from the floor board making summers miserable. What can i do so that when the unit is off no air comes through any port?
  • Hi,
    I have a 96 Bonneville and got the a/c fixed a few summers ago and then it went out again the next summer. I don’t want to dump a ton of money into it but it allows heat in thru all vents, floorboard vent, and defrost at all times. When i turn the blower on i can switch between floor, vent, and defrost, but when everything is off heat continues to flow in thru all vents though the blower is off. Please help!!!
  • I have a 96 Bonneville with 200K milage and have been experiencing the heat issues that evidently many other bonneville owners have suffered. (i.e. the system closes the blend door after about a minute of operation and only cold air comes out after that).

    Reading through all the various discussions on this particular issue (and trying all the various solutions offered), I've come to the conclusion that it's something that is a) quite common to this particular heating system, and b) even if I replace all the electronic parts (have replaced the "head unit" already), there's no guaranteeing this won't happen yet again.

    So, my question here is simply how do I go about disconnecting the actuator motor (hopefully without damaging it) to where the blend door stays in the "heat position"? Any pictures would be GREATLY appreciated!

    Thanks in advance for any and all help offered!

    Signed,

    Tom, aka Cold in Allentown, Pa :(
  • By the way, just so we're on the same page so to speak, this is a picture of the dashboard...

    image
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,045
    Most likely your actuator has had a gear inside crack which reduces the pressure fit it has on the axle which extends out of the actuator to actually push and pull on the rod to the blend door.

    The Buick has easier access to this actuator than the Bonneville due to a different design of the dash. Some had pulled the glovebox door forward so they can see through to the top of the heater box or removed the door. There is a view to the rod which has a brace rod in the path but there is a hole in the brace allowing a view of the rod. They have actually ducttaped (IIRC) a clothes hanger wire to the rode to be able to manually adjust it, i.e., keep it from moving on its own.

    The actuator can be removed by two screws and disconnecting the electrical connector, but space is tight. Use methods to avoid dropping the screws or losing the sockets if they come off your wrench.

    Here's a link: link title
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