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Pontiac Bonneville Heating/Cooling Problems



  • dmx6dmx6 Posts: 7
    I have been asking questions and some seem to think the problem is the program box on the heater case behind the glove box. Mine does make a noise that makes me think there is something wrong in it. Sounds like something trying to move and won't. The other issue is the temp reading flashing--I thought it would only flash when the control was engaged but tonight the system was off and the outside temp was showing on the face of the controller and it was flashing. As far as my cables being bad--I cleaned them with water mixed with baking soda and that took care of the acid corrosion. Replaced the bolt and spacer so my contact is good. My friends in the salvage industry tell me the programer box on these cars sell as fast as the cars come in--they can't keep them. Something is wrong-I just wish I knew what it is for sure. I don't want to start replacing parts till I get it right.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,054
    You can take a look at your box. You have the dual auto control since you have the digital display.

    Several people seem to have had failures after battery changes. I'm not sure what that means. The units need to be turned off. Then the key turned off. ANd then the negative cable disconnect first and reconnected last. From other places I'm reading I'm not sure what you problems are.

    Does the system switch to putting air out the defroster instead of the floor or dash vents? That can be a sign of the vacuum connector at the programmer box $400 box not letting the vacuum through. No vacuum means the doors are set to the defroster for safety.

    The noise you hear may be the real clue. But you're saying both of you don't get heat. You need to watch the movement of the levers at the bottom of the unit while it operates to see if it's smooth. Take off the hush panel under the dash that's a thin plastic layer above the passenger's feet. It's about 3 screws and couple of taps at the floorboard. And watch the white plastic lever that moves the heat vane inside the heater box. It is #11 in the attached picture.

    It comes from the programmer box and moves the vane. It snaps over the rod that sticks out of the heater box to the left. It just clips on; it looks like a screw thread but it's not.

    You could unsnap it and move the heater vane all the way ?left? I think and see if you get hot air. The car should be at 90 degrees control setting and the threaded rod should beall the way to te left when the two are snapped together again to calibrate.

    Your motor inside the programmer may be skipping gears and not moving the rod.

    Also the actuator #4 for the passenger vane to adjust the temp up or down from the main setting usually is one shown as having cracked a plastic gear inside and losing calibration.

    I know of one Pontiac owner who installed a coat hanger wire through the glovebox and to the heater vane to adjust it till he could replace the actuator for one of these--and I guess that would be for the lower one. The programmer boxes just sit on the end with two screws. There is a little connector to the actuator on top and a large wiring connector that snaps to the programmer. The connector for the plastic tubes probably WON'T come apart after you remove the little tape in the middle. I'd suggest cutting the lines and reconnecting inner and outer colors (make a list and picture before you cut) with 1/8 inch rubber hose (free from scrap box at autoparts store? Or buy a 6 inch piece).

    See if your problem is electrical or vacuum. See if hot air is coming out at the defroster. The fix for vacuum line collapse is free.

    Dual AC in 1998 H body
  • dmx6dmx6 Posts: 7
    It is apparent I am not the only one having this problem. I just really thought someone would have found a solution to it. I pulled the glove box and underside cover and still can't get access to the top of the control. There is a vent that goes across the top area and it blocks access to the control. I guess the dash assy must be pulled to access the heater box---does anyone know of another way?

  • Hello everyone who has a moody car like me! :0)

    Well, I'm not sure if we have the exact same problem, (or if it is just coincidence), but I had no heat (sometimes) and it had problems only after replacing the battery. My heating problem was the THERMOSTAT. I had it replaced and now have heat. My car was overheating a little bit too, while the heat was working for 20 seconds, then not at all. There are a million more problems with my Bonneville, but at least I have heat now for the rest of this Colorado winter! Hope this helps someone.

    Best, Angela
  • dmx6dmx6 Posts: 7
    Mine is fixed--it was the actuator motor on top of the heater box. Had to remove dash pad assy for access--the part lists for approx 100.00 but less than the programmer!! At least now there is heat coming from the heater assy!!!
  • That's awesome! Mine however, is not fixed. It worked for a little while and now does not. I'm about ready to give it up. People keep overcharging me because I have boobs! Frustrating! I have antifreeze leaking from the intake manifold gasket? Or something? Could this affect heat? I have no clue. Any advice aside from blow it up and take the city bus? Angela
  • My heater does not work. Dealer ran check and said it is due to a short in the a/c programmer. He will fix it for $1,200. I have found a junk yard with one in it, but I can't see how to remove mine. I have tried from the underneath with no luck. I paid $15 to another site for the info, but all they said was to remove the glove box and all the hardware around the sides. I did but a metal bar with pn 395233 stamped on it doesn't come out, andeven if it did I can't see how to remove the duct works either. Can someone explain how I gain access to the A/C programmer? I have also seen on this site where people have been able to activate to control valve with a coat hanger. I can't even see to programmer, let alone attach something to it.
  • mike235mike235 Posts: 11
    Hi Ralph
    I have had the dealer tell me the same thing and I to purchased a controller from a salvage yard and replaced mine, but it did not correct my problem. Not saying it won't yours but just so you know. Look right directly behind the glove box from underneath and the controller sits vertically up in the dash. There are two small (think metric) screws holding it in that you can get to from the underside. It is not easy but keep at it. I used a small wrench (think 6.5 mm comes to mind), however once you get the two screws out the controller will come loose. Then I had to reach (contort) my hand up behind the controller and unplug the wire harness on top of the controller. Its not easy either and will test your patients, but it can be done. Then the controller will drop down enough so that you can get it open. If you choose to do it the way I did, the air hoses (to power the vents) all go to a small manifold inside the controller and unplug every easy all at once. Then you just do everything in reverse and install your new controller.
    I think my next attempt is to get to my actuator motor and look over the linkage/gears and such as mentioned in posting 43 and 46. I myself have already wasted $300 plus on my new controller and still only get heat some of the time. But good luck with yours and I hope I was able to help you in some way. Keep us posted. Mike
  • dmx6dmx6 Posts: 7
    Angela, your leak on or about the intake on these cars is usually a cracked intake. When aftermarket suppliers make parts it is a good indication of problems with those parts thus there is a market for them and they make this part. It could be the gasket but what I have seen is a problem with the intake. It is not metal (the lower part is but the upper is a composite material) and the upper is the problem most times. Are you having to add coolant to your system?
    Does your digital face still flash the numbers? If the numbers don't flash on the digital face there should not be a code on the heater/ac system memory thus the system indicates no problem there.
  • dmx6dmx6 Posts: 7
    Ralph, look back on post #43 and check the diagram that was attached to it and you will see how they programmer is attached. Hope you got it fixed--

    Mike, what happened to yours? My problem was the actuator controller on top of the box. I tried to open the thing and could not with out really tearing it apart so I purchased a new one and put it in. Several hours of work but my wife is not talking about no heat!!!
  • I have a 1998 Pontiac Bonneville and I have to start my car and hit the heater motor to turn the heater on. But when im driving it will turn off when i hit a bump or turn on whenever. I never know. And if I leave my car running too long sitting still it over heats. I dont know anything about cars any help would be great. I have two kids one a one month old premature baby and i need to get my heater working asap its cold!!!
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,054
    If hitting the blower motor under the hood area behind the motor is enough to turn it on, that's the prime symptom of a worn out blower motor. It's a tight fit, but the 5-6 screws hold the blower to the firewall part of the heater box and it can be worked out.

    Replacement motors for the blower are available aftermarket. Connect the blower motor and test it for running before bolting it in.
  • Thank you so much for the response. The lower intake is just beginning to seep out coolant, it is not leaking bad yet. I think I was quoted about $300 to repair that. However, I am told that every sensor on my car except for one is reading that it is bad. So, I'm not sure if the whole dang computer is fried or what is going on, but I'm wondering if it is worth fixing at this point. There is also an ABS issue, with the sensors coming on and the car thinking I'm on ice when I'm not. Also, shocks and struts, ball joints, and tranny and brake flushes are needed. Everything is more expensive because I have a supercharge engine. I paid $80 for the thermostat to be changed, and that didn't solve the problem. I took the advice of a previous poster, and set my heat to 60 degrees for a minute, then up to 90, and sometimes that works. Sometimes I have to turn the car off and back on to get the heat to work, and sometimes no matter what I do it won't work. Those are usually the ridiculously cold days, of course. Single mom's shouldn't buy used cars. That's all I can come up with for a solution at this point. I'm a full time college student, and high dollar repairs are needed. Sigh. I do so appreciate your help, though. I will keep trying to figure out what this is and hopefully can come up with some car repair funds soon. I paid almost $5,000 for the car 6 months ago, so I would like to fix it if I can. It's a beautiful car and the engine is great... for what that is worth! There is just over 100,000 miles, which isn't too bad for a 1995. Thanks again, Angela
  • Sorry I haven't replied sooner, but I just stopped using my bonneville for now, hoping someone would figure it out. So you say by replacing the actuator controller and that corrected your problem? How much did it cost you?
  • dmx6dmx6 Posts: 7
    I put the part in myself but the part cost $60.00 to purchase. I imagine labor might be high because the only way in is to take the dash assy out. My car has the console which took longer but the one without the console is easier to deal with.
    Good Luck!!
  • Thank you very much for your help, I will be doing it myself once I get the part. You wouldn't happen to have a part number would you? And did you learn any tricks to getting the dash off/on? Or did you break any clips/posts, I would assume that is how it is held on there? Thanks again for your advice. Mike
  • Thanks to some info on this site I changed the programmer myself. One thing that made the job easier was that I added about 18 inches of wire to the 6 wires that are in the connector on the top of the unit. That allowed me to have the unit on the floorboard and I could see the recepticle. It also got the unit out of the way of my hand.
  • I change the programmer and now have heat, but no air. The dealer wants to change the accumulator for about $1,000. Auto Zone has an accumulator for $33, so now I just need to know if anyone has any tips to offer.What seems to be confusing in the manual is the part about draining the refrigerant oil. It seems you remove the Schrader valve and measure the amount that comes out, and then add that amount plus one ounce. Where and what is the Schrader valve? Can anyone help? Thanks!
  • Mike, you don't have to remove the dash panel to change the programmer. Go back to #43 in this section and call up the diagrams posted at the bottom. The progtammer is right under the glove box with about 6 or 7 hoses connected to it. It is held in with 2 screws. One is on the duct and the other is closer to the glove box. They are both 7 mm. Cut the hoses and get some 1/4 in hose to go over the existing hose when you replace the unit. I went to the dealer and found all bonnevilles from 1996 to 1998 have the same programmer. You will have a problem disconnecting the connector on the top. There is a little tab that is pushed in towards the rear of the car to release the connector which pulls up. Good luck if you haven't already done it.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,054
    Why do you need a programmer. What are your symptoms?

    The programmer is the box down by the heater that has vacuum tubes going in and out that control the vacuum doors on the heater box to direct air to the right places. I assume you have the automatic air with the digital temperature readout? It also controls the actuator that varies the temperature door to maintain the right temperature.
    look it up under HVAC or heating and air conditioning
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