Pontiac Grand Prix Climate Control/AC



  • swamp_gatorswamp_gator Member Posts: 3
    Yes they are vacuum controlled. If you pull out the glove box on the passenger side you will see a control module with vacuum lines going to it. You can check the vacuum at each individual line to see which vacuum module is bad. They are all color coded so you will be able to trace it easily. The vacuum modules are replaceable without pulling the dash. Hope this helps.

    Marc in Sunny FLA
  • mcguire5161mcguire5161 Member Posts: 2
    It has to be a leak in the vacuum line that controls the flaps inside the dash that block the ducts except for the one you set the control knob to. It then closes off all ducts and leaves the selected vents open. It's all run by vacuum. I had this same problem with my 1998 Dodge Ram pickup. You should research where the vacuum line is located. I think it runs from the intake manifold and end up under the battery where it attaches to a fitting. Usually the battery will end up corroding the line over time. Thats more than likely the problem.
  • mcguire5161mcguire5161 Member Posts: 2
    I have a 1997 Grand Prix GT 3.8L not supercharged. The guy we bought the car from said that the heater blower only works on level "5". I have read a bunch of these forums and nobody has really figured it out. I have heard two things that sound most likely to be my problem. One is the fan ignition switch? Need to research and find out what that is. The second thing is the resistor. Not really sure here. Also the rear window defrost won't turn on and stay on. I have had it stay on for maybe ten seconds and then the light turns off. I don't know if that could be related to the blower problem or not. My thoughts are that someone may have used something they shouldn't have and sliced through one of the delicate wires. I haven't got up close and looked at the rear window yet. My biggest concern is getting the blower motor to work on all five speeds. Anyone have anything?
  • smaugzzsmaugzz Member Posts: 1
    The level five heat is the blower motor resistor I'm positive of that. I dont have a clue as to the rear defroster and the resistor can be purchased at any auto parts store. this video is of a sunfire but the process is the same http://www.youtube.com/watch?v=EsKIRuK7his . Good luck with the defrost

    (personal experience replacing 2 resistor based on three years automotive schooling)
  • joeg1joeg1 Member Posts: 18
    My 98 Grand Prix GTP's CJ2 Digital Heater - A/C Control is putting out only 0.01 volts at C11, "Blower Speed Control Signal," when the CJ2 connector is back probed and the defroster is set to high. I have performed the diagnostics, "Blower Motor Inoperative at Any Speed," several times always reaching the final step, # 29, which is to replace the Heater - A/C Control.

    I replaced Heater - A/C Control with two different units - both represented as good - and still only 0.01 volts at C11 where the factory specification is 0.5 to 7.0 volts. All three Heater - A/C control units function correctly in all other respects and in the diagnostic mode position 00 is 00.

    Any ideas? This problem has bedeviled me for months.

    Many thanks,
  • mcsherrysmcsherrys Member Posts: 1
    I had the same problem with my 97 GTP. Turns out that the hard plastic vacuum line located under the windshield fluid reservoir and to the rear of the battery deteriorated and vacuum was lost. I reconnected it with a new vacuum hose and now it works great!
  • notacargeniusnotacargenius Member Posts: 2
    I am having the opposite problem from everyone here. My AC is registering -9 to -16 degrees outside when it is 107 degrees, so the AC doesn't come on. It only stops working at the hottest part of the day. It works in the morning and at night when I don't need it, of course:) Does anyone have any idea what this could be?? I have a 1999 pontiac grand prix.
  • notacargeniusnotacargenius Member Posts: 2
    In case anyone else has this problem. It was the exterior temperature sensor at the front passenger side of the car. By the radiator almost on the plastic of the car. It was a $9 part and easy to fix:)
  • rockyford1rockyford1 Member Posts: 1
    Hello, I have the same problem. I have a 1999 Grand Prix..It just started doing this after I changed the battery and alternator. We have checked all the fuses and finally ended up changing the resister..and still the blower will only work on 5 and it is affecting the running lights..if the blower is on i have no lights. We have run out of ideas. I havent taken it to a garage my backyard mechanic has spent hours checking wires and fuses. Has anyone else had any similar problems or solutions??????
  • harts27harts27 Member Posts: 1
    I have the same problem with the daytime lights and the rear defogger. I am worried that the resistor is not the problem. I have had my mechanic look at it but he could not give me a reasonable answer other than replace the entire HVAC. Has anyone figured out what is causing this?
  • gmcustsvcgmcustsvc Member Posts: 4,252
    I apologize for your frustrations. Can you send me your VIN so I can look into it? Have you spoke with a GM dealer? I look forward to your response.

    GM Customer Service
  • sean62sean62 Member Posts: 1
    My heat in my 07 grand prx isnt working hrdly a all. I have filled the coolant level ad th fan works fne but vry little warm air comes from the heater. Anyone ha this similar iue on their 2007?
  • madron67madron67 Member Posts: 1
    If you #5 setting doesn't work but 1 thru 4 work it is a fuse. your fuse box is behind the glove box. there are 2 fuses for the HVAC fan. 1 is for 1 thru 4 and the other is for the hi setting. I hope this helps...
  • temersontemerson Member Posts: 2
    I have had the same problem with mine the mechanic replaced blower motor and resistor and now he is going to replace the ignition it is not letting enough electricity get to the blower.
  • temersontemerson Member Posts: 2
    I had the same problem replace the ignition and problem should be fixed.
  • prein812prein812 Member Posts: 2
    I have the same problem have had the thermostat replaced and system bled twice. Any ideas would be greatly appreciated
  • prein812prein812 Member Posts: 2
    Get a thermostadt from the dealwer not a car parts store cuz the dealer part is the right one and the problem will be fixed. If you get it from the auto store it is a general thermostadt and can be used in that type engine
  • camaromikecamaromike Member Posts: 1
    I have low air flow in automatic climate control heating mode. In AC mode, fan goes on full blast at 60 deg F. In heating mode, with control set to 90 deg F, I get some flow. Went to dealer, and was told probably blend door. Later told it was blocked heater core - over $600 to repair. Didn't go through with repair as it may be something else
  • emarkeremarker Member Posts: 7
    I think I finally figured out why my A/C wont work anymore. The instrument cluster went bad but I have a stupid question. I have found a part but the part numbers DO NOT match. Does this matter? Why do part numbers have to be the same? As long as the part is compatible with my car, then it shouldn't matter, right?

    Any and all replies appreciated.


  • emarkeremarker Member Posts: 7
    If I found replacement parts, does the NEW part number have to match the OLD part number? Part numbers shouldn't matter as long as the part is compatible with my car, right?

  • leslieannmc1leslieannmc1 Member Posts: 1
    Its been some time, but im having this same issue... looking for advise
  • jimm4466jimm4466 Member Posts: 1
    I have a 2003 Grand Prix and the blower appears to work fine and the heat appears to be hot. The problem is that you can hear the fan blowing very well, but does not appear to come out of the vents that you have directed it to come out of. For instance, if you turn it on defrost, very little comes out. It seems like it wants to come out the correct vent but something is holding it back. Anyone have any ideas where to start? The car does not have climate control. It has manual switching with driver and passenger heat controls
  • jfisshjfissh Member Posts: 5
    Hey guys, after a few years of putting up with my problem I finally got it fixed.

    First, I know that not everyone in this thread is having the same problem, so I will describe my solution so that you know if it pertains to your problem or not.
    • My fan would not work on any setting except 5 (highest).
    • My headlights would turn on and off quite rapidly, but not constantly. The fan seemed to have an impact on when the headlights would flicker. If I had it set on anything inbetween off and 5 (high) the headlights would flicker. To stop them, I would simply override the automatic headlight sensor and just turn them on. (Grand Prixs have automatic headlights, but there is a dial that you can turn them on just like any other car out there)
    • My little display screen was really dim and would also flicker and glitch out with the same consistency as the headlights. The information was really hard to see and most of the time it wouldn't display the correct information. This is the screen that shows you your boost if you have a super charger, which doors are open, your average MPG, range, and oil life.
    • I was not able to turn my rear window defrost on or toggle the A/C button.
    • Finally, every once in a while all of my electronics in the car would just short out and everything would turn off and then back on. This included everything mentioned above and also my radio and instrument panel lights. The car would remain running, however.
    Just a couple of months ago my car started doing something new. Occasionally, it wouldn't even try to turn over when I turned the key. At first this happened quite rarely and it seemed to resolve itself if I rocked the shifter back and forth from park into gear and back. In reality that wasn't doing a single thing, but I thought it was.

    It kept getting worse and worst and just the other day I tried for 10 minutes and the car still wouldn't start. I had enough and brought it in to get fixed. I thought it was the neutral safety switch, so that is what I told the mechanic.

    I got a call and they told me that it was my ignition switch that was bad. Okay. "Fine", I thought. That will fix the problem of my car not starting.

    I was in for a big surprise. Once I got back in the car... everything worked... everything. YES!!!

    So after all of this time, all of my electrical problems were due to the ignition switch!!! Who would have guessed?

    $550 and a day later and all of my problems are solved. Hope this helps someone else. It might save you a couple hundred of dollars if you can do it yourself or it could spare the mechanic looking for the problem, which will save you money.
  • jfisshjfissh Member Posts: 5
    I think I have your solution (if you still have your Grand Prix)

    Check it out here: http://townhall-talk.edmunds.com/direct/view/.f0f81eb/230!keywords=#MSG230
  • morgan71morgan71 Member Posts: 25
    Hello all,

    I am a little stumped on this one. When I turn my fan on my a/c switch with the snowflake symbol is always coming on now. It didn't do that before. I have done some light troubleshooting. When I turn the ignition without starting the car, I turn the fan onto a low setting and it comes on, I pulled the fuse out from the panel on the passenger side fuse box and the fan stopped working but the light also went out. As soon I put the fuse back in the fan came on and the light was back on. All of the fuses for it are good. I've read some other info from other sources that said it could be a board that controls the ac climate controls might be going bad.

    I just want to be sure if its not the actual climate control panel itself.

    Any info and help would be greatly appreciated.
  • 98streetshaker98streetshaker Member Posts: 1
    I have a 98 grand prix gtp and my blower controls will not switch off of windshield setting. It is the digital controls and will not switch to vents or floor. It says it does but there is no air coming out of anything but windshield
  • chrisprixchrisprix Member Posts: 1
    Hey everyone,

    I SOLVED THIS PROBLEM IN MY 1999 Pontiac Grand Prix.

    In my car, the driver's side was only blowing like normal temperature air (not HOT and not COLD, while the passenger side was ice cold.

    So, I read so many postings on a zillion websites, watched youtube videos, and thought for sure the problem was the actuator on the driver's side. If you don't know what the actuator is, it basically controls whether to open the 'hot air' or 'cold air' into that side of the vents. Google search it, or youtube it, and you'll learn about it. I figured it must be kinda left open or something.

    Anyways, I replaced the driver's side actuator, which was a NIGHTMARE to get to....but anyways, I did it, and it did NOT solve the problem.

    Bottom line, I decided to buy a can of A/C Pro to recharge the system. The can, with the gauge and hose was like $40. Honestly, I didn't think it'd work. I pretty much figured that since the passenger side vents blew ICE COLD, the whole system should be fine, and something else has to be not allowing the cold air to blow out the driver's side....I thought maybe the temperature controls or something weren't working.

    But..................... IT WORKED!!!

    The driver's side vents are ICE COLD again!!!! Amazing!

    Anyways, that was my fix. Maybe it'll work for you.
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