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Pontiac Bonneville Heating/Cooling Problems

I have a 1993 Bonneville SSE. I was not getting any heat. I sent it to a local garage and they replaced the temp sensor and the programmer. The mechanic said that it wasn't the problem and is stumped on why there is still no heat control. The mechanic is stumped with the problem and rigged something so now the heat doesn't shut off. Does anyone know what this could be?????


  • I have a 1998 Bonneville that the battery died in last week.
    I replaced the battery as alway removing the negative cable
    first then the positive. put in the new battery hooking up the
    positive cable then the negative. when I started the car I noticed that the temperature that displays on the climate control screen was flashing. It flashes for about a minute then stops. The air conditioning works fine but if you turn the temperature up to 80 or 85 so it should be heating it does
    switch the air from the dash opening to the floor openings but the air is cool not hot. If you turn the heat all the way up to max (90) and shut the car off and restart it then the heat will work but if you lower the temp till the air conditioning comes back on and then raise it again you get cold air again. Any Ideas ? Thanks

  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    I've read about this before. I'm not sure if it's specific to Bonnevilles of applies to Olds and Buick as well. There's procedure for calibrating the programmer and parts associated with it.

    I'm guessing... that turning the temp all the way to 90 degrees and let it sit for a minute or two and then lower the temp to 60 and let it run for a few minutes, it should get the settings for the movements on the control arms again.

    I'll check my factory service manual for 98. Gimme a day. Someone else may have it quicker.

    People who have had this problem said it corrected itself after a while.

    Just a thought, are the terminals at the battery clean of corrosion? Is the double connection on the positive clean between the two cable ends? That causes a lot of problems.
  • I will try what you said about turning it up to 90 and down
    to 60 Thanks. If you could check on the procedure from your
    service manual that would be great.

  • I tried running the temp up to 90 and down to 60 and
    also tried unhooking the battery cables and touching them
    together for a couple minutes to drain any stored power and I
    still can,t get heat. Any idea's- Thanks

  • I have the same problem with my pontiac it is a 1996. I just had the air pump replaced and the controller started to blink and I have air conditioning but no heat. If you find out anything about your car please post and let me know what you did to fix the problem. Thanks Jeff C.
  • The fan on my 1998 SSE works when it wants to. If I leave it on it'll turn off and on as I drive. Doesn't matter what mode or if its AC/or heater. I've changed the blower motor, changed all the fuses, swapped the relay swith with a different one. Does anyone know what my problem is?
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    Most likely it's the blower motor control module. It's the equivalent of the resistors that are in manual heater control cars in the old days. It sits on top of the box near the blower motor. You have to loosen the one or two bolts holding the relay center that's above the heater box there to get it out of the way. It's held in by a couple of screws and is a circuit board. Often they fail in the on mode and the blower won't shut off. Ours failed on a 98 where it would go on and off and operate at funny speeds different than the regular 6 speeds settings that can be picked.

    I was told they're available at Advance Auto as well as dealers,, Or even as a pull from a junkyard.

    You should follow the power wire from the blower motor and see it goes to the module to help find the module. You can tap the power wire and check the voltage to ground as the blower motor slows or stops and see the power dropping that's coming from the module.
  • jhaas5jhaas5 Posts: 1
    I had the same issue with my 1998 SSEI Bonneville. I replaced the blower motor control module, which is located in the pictures as directed.
    It worked out wonderfully.
    I pulled the part from a junkyard, for $10.
    Thanks for the advice.
    Please post more if this has solved anyone else's issues.
    Thanks alot.



  • I replaced my blower motor control module. I have air conditioning or het coming out of defrost orm follr vents only. Why doesn't it come out the center vents?
  • Sorry about the previous question....

    I did replace the blower motor control module but have no air coming out the vents in the center. It only comes out the defrost or lower vents.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    You likely have a problem where the soft plastic connector that joins the 4-5 plastic lines for vacuum inside the programmer box with the lines coming from the heater box and the car's vacuum (purple) has thin black plastic that was inside the connection and softens with age and blocks the flow of vacuum.

    If the rest of the controls work as in defrost which is no vacuum to any of the control motors, and heater works which blocks off the air flow with a motor vane at the bottom of the box, you most likely have the AC vent problem.

    The easiest fix is to take out the programmer, or gain access, and cut out the connector and join th internal plastic and outside with 1/8 inch rubber gasline pieces or slip aquarium tank line over the two ends to join them.

    At least one person said they were successful at taking apart the rubbery plastic connector and punching a hole through the black nipples that collapsed and putting it back together. But usually the plastic has soften and sticks together, pulling apart in chunks.

    I can send pictures to your carspace email account of the piece you're looking for. Is it an automatic temperature control system?

    A good check to be sure the vacuum motor works is to switch a vacuum line from another one of the vacuum units to the one for the AC vents and switch the controls until that one operates with vacuum through the line.
  • Yes, it's an automatic temperature control system. The pictures would be helpful. This is getting to be a very expensive adventure.
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    I got about 6 inch of 1/8 gas line from a NAPA store when looking for a size that would slip over the 1/8 outside diameter hard plastic line used in these cars. It was free from their scrap box.

    The programmer sits on the corner of the heater box and has two screws holding it on. It is possible to remove the cover by unsnapping the two clips holding it in. But I'd take it loose to have more freedom.

    Click on the pictures to see larger views. The black plastic under the passenger side has about 5 screws total holding it in place to quiet sound from under the dash and firewall. The glovebox has about 7 screws on the bottom hold its hinge to the bottom of the dash.

    Then you have a good view. The large bundle of wires into the programmer can be removed, but I don't remember if you have to do that. Make a list of the colors of tubes inside the programmer mating up to the different color coming out of the plastic connector. Cut one tube that goes to the AC and reconnect it or cut all 5 tubes.

    Remember someone said there's an aquarium air tube that fits over the outside of the 1/8 inch plastic.
  • My blower motor would intermit stop working. It would work in the morning, not at noon, but then later in the day. This sounds crazy, but the longer you drove it, the more chance I would have of it working.

    I am having the same problem but is becoming less intermitt and more permanent. I have noticed that it blows stronger when driving and less when stopped. I have also noticed that it will stop and start while going over bumps. What do you guys think, I do not have automatic temp control.
  • I have an 1989 Park Avenue the tranny went out of , I pulled the blower motor control module out of. The cooling fins as I call them were about an inch shorter but the numbers on the sensor were the same. My heating and A/C are working fine. I thank you for your help and the money you surely saved me.
  • I am a new member and see the same problem that I have with my 96 Bonneville posted but no answers to the problem. Has anyone the answer to why my heater will work sometimes and not others. I took it to the dealer and the diagnostics said the problem was with the "heater & a/c programmer". They said $700 and change for a new one so I found one at a salvage yard for $175 anyway, after changing out the programmer I still have the same problem. The display will flash and nothing but cold air will blow most of the time. I can switch the air flow from floor to dash and defrost ok, but most of the time I have no heat. I did replace the battery a short while ago, would this have anything to do with it, need calibration maybe? Its very cold right now here in Michigan can someone please help me?
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,048
    #1: Is your radiator full (not just the reservoir tank). Open the cap, when COOL, and look. Low coolant means the heater core gets an air bubble--air doesn't transfer heat.

    If it is low, fill. Run car until fully hot and speed up motor to 2500 for a few seconds and repeat this 5 times to push water into heater core and get the air bubble out.

    #2: If radiator full when running motor is hot, are both heater hoses hot even with blower running at full speed. If one is cooler that means there's not enough hot water flowing through fast enough to deliver hot air from the fins. The water is getting cooled by the air going over the fins and won't deliver hot air. Both hoses should be hot.

    Are you saying that the blower speeds work okay? One problem is the blower control module which is like the resistor coils for old blowers is an electronic unit on the auto temperature control models. It sits on top of the air box next to the blower motor under the hood. The relay center needs to be loosened (1 or 2 bolts) and raised to access it. Available at Advanced Auto, etc.

    The programmer sometimes loses its settings when batteries are changed. It's best if the heater is turned off before doing anything like that. When you installed the new programmer did you have to connect a rod from the programmer that was white plastic (yellowed) and snapped into a metal threaded rod coming out of the heater box? IF so, the heater should have been on full heat and the unit have time for the actuator inside the programmer to pull all the way to hot and then you pull the metal rod to the right and snap the two together.

    See if you reach under the dash and unsnap these rods, if you move the metal rod left and right you can control the heated air temperature. If not you might have a partially blocked heater core. But usually it's the evaporator core mentioned blocking up with debris.

    I am assuming yours is auto temperature control and is like my 1998 leSabre. I replaced programmer with a 95 Buick programmer when I messed it up correcting the vacuum tubing block problem that cars from 97 on seem to develope.
  • Thanks for the input Keith. I think you are on to something with the air pocket and blocked heater core idea. But I checked my radiator and resevoir but both levels are fine. However, the fluid is brown and looks very dirty with some solids. Also the hoses going to the firewall are not the same temp. One is much cooler and like you said appears to have a partially blocked heater core. I am going to take it after lunch today and have it flushed and re-charged, I sure hope this works and will post again with results. Feel free to advise more if need be. Thanks again for your help with this matter. Mike
  • No go, still no heat! Took Bonneville to garage and they took a look at the coolant and said it did not need to be flushed. Had the oil changed and then we spent the next 15 mins with the engine running and radiator cap off trying to get the air out of heater core. Had some bubbles but appairently did'nt get it all out because its still cold air blowing out. What I don't understand is why do I have perfect heat when I shut the car off for just a few seconds and start it back up. I will get hot air for about 20 seconds then the digital display starts blinking and the air goes cold??? Anyone have ideas? It's still very cold here in Michigan!
  • Mike,

    I have a similar problem with a co workers '98 Lesabre. I am going to try the module first. She is getting off and on heat so I am not thinking there is a water problem. Obviously, I will check the inexpensive things first. I will let you know what works.
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