I have a Pontiac Grand Prix GT 1998. She runs great except my A/C is now acting up. I first noticed it a few weeks ago. I was driving and it was almost like someone had turned the air down so it wasn't blowing out as hard. I looked down and turned my knob and it was sitting at 60 (my car has duel climate controls so I checked to make sure duel/passenger side was off and not interfering as well). Few seconds later it all stopped. Lights on the A/C were still on and I could still adjust the temp. I turned it all the way to 90 thinking it was a cold air issue and still nothing. I turned it back to 60 and kept driving. It would randomly turn on and blast glorious cold air and then die again. The longest it has worked continuously since this first started was about 2 days. It's now getting up in the 90s outside and it's miserable to drive anywhere. Please help! I'd like to fix this on my own so any instructions would help as well. I'm a pretty handy lady but haven't had to deal with an A/C issue yet. Thanks!

  • I have an climate control in my GM truck with some issues. Someone suggested (via research) that the control may need to be reset. To do this you'd unplug the battery for at least 30 minutes. When you plug it back in, the control is forced to reset itself, which might bring it back into function for you. It's at least worth a try. If it doesn't work, it may be the controller or the temp sensor which might be giving you issues, but that's just a guess. Jun 19, 2014 at 14:53
  • I thought about the thermostat sensor myself but haven't checked it out. Someone else had mentioned maybe a blower issue, but guess that's controlled by the sensor? I'll try the battery thing - I'm not going anywhere so I've got time ha. Thanks!
    – Kaylen
    Jun 19, 2014 at 15:32
  • Since the motor comes in/out, I doubt that's the problem. It will either run, or it won't (it might make a lot of noise while running, but that doesn't seem to be the case here). There is a motor resistor which may go bad, but when it does, it blows the air on full blast, so it wouldn't be that. In my mind that leaves either the controller (could be broke or needs reset) or the temp sensor, but I'm not an auto HVAC person, so it could be other things I've not given consideration. Jun 19, 2014 at 15:34
  • If I take it to like auto zone, the sensor should show up on the diagnostics test, right? I haven't had one done on my car for an A/C issue yet.
    – Kaylen
    Jun 19, 2014 at 15:43
  • 1
    No, I believe the sensor will not show up in the diagnostic. I do not believe the climate control is hooked through the CAN-BUS to the computer, especially not with a car manufactured for the 98 model year. The only thing which would show up is that whether the A/C compressor is told to kick in. This is because the A/C controller tells the computer and the computer sends a signal to the relay and the relay energizes the clutch on the compressor. There's not much else talking there. Jun 19, 2014 at 16:28

2 Answers 2


Has anyone messed with your A/C or Freon recently? If the compressor turns on then instantly stops it could be either you are lacking freon or there is too much in the line. If you over charge most compressors will turn off if it notices the pressure is above a certain limit. When it gets hot outside it also causes the pressure to rise which can cause this issue. What was OK at 80 degrees is too much at 90+.

I'd take it to a Midas or A/C shop, or if you feel comfortable, go to Autozone and buy a recharge kit with a good gauge on it. Find your low pressure port(http://idqusa.com/wp-content/uploads/sites/2/2014/02/98-pontiac-grand-prix-1024x768.jpg) for your A/C system, hook it up and turn your A/C on high. Then follow the instructions. $30 at most for a DIY kit at most auto stores.

  • Last thing I had done on my car was an oil change. That was a few weeks before this started happening. I read about the recharge kit as well.
    – Kaylen
    Jun 19, 2014 at 16:41
  • 2
    I think you're right: this sounds like the refrigerant has leaked down to a marginal level. The compressor is turning off right away because there's not enough for it to compress. Now, that said: if the refrigerant has leaked out, there's still a leak in the system that needs fixing. I was just reminded of that fact when I didn't replace the O-rings before recharging the system: chat.stackexchange.com/transcript/message/15399775#15399775
    – Bob Cross
    Jun 19, 2014 at 19:02

Make sure that there is not any Trash between your condenser and radiator. Leaves and grass will prevent it from cooling properly and thus making the pressure rise to a point where it will cut off automatically.

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