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Thread: Stalls When Stopped & AC/Defroster Turned On

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  1. #1

    Stalls When Stopped & AC/Defroster Turned On

    The strangest thing is happening to my 2000 Galant ES. If I am moving and turn the AC or front defroster on the car continues to run (although i do notice that the tach jumps around a bit when i take my foot off the gas). However, when i come to a stop with the AC and or the defroster on, the car will stall out.

    With no AC or front defroster on the car idles fine. When moving the AC and defroster both work fine. I am not quite sure if its the compressor since it still works!

    I recently had the timing belt done so the battery was disconnected (I had to enter radio code to unlock it).

    Does anyone have any ideas on what could be causing the car to stall out when i am stopped and have AC or front defroster on???


  2. #2
    Most cars turn the AC on to defog the front window when you turn on the defog setting.

    More than likely, it's your compressor causing extra drag on the engine. Either there is an issue with your compressor or the extra burden it puts on the engine is exposing some other issue with your engine.

    2000 Galant ES

  3. #3
    TGC Regular P'NOYcaL's Avatar
    Join Date
    Bergenfield, NJ
    You will have stalling issues every time your battery gets disconnected but after a few days driving your car you shouldn't have a problem.

    Everytime I install my CAI and Short Ram i always have to disconnected my battery and my car will always stall. After replacing my battery just today, my car stalls when at a stop also when parked but at the end of the day it was all good. But if your having that stalling issues "Everytime you turn on your AC or Defroster while parked" it could be your battery itself that needs to be change soon enough, as I said I had to change mine today.

    I think its because something resets when you disconnect the battery. That's just according to my experience.
    Last edited by P'NOYcaL; 03-30-2010 at 10:06 PM


  4. #4
    I have my battery unhooked a lot and I never have engine stalling problems. It's a nearly 7-year old battery. There is something holding the engine back. i would check the compressor and make sure the pulley is not seized or with a bad bearing that could cause it to catch the belt. If the pulley is not rotating freely it will slow down the crank and could possibly cause the stalling out at idle.
    Jigz-TGCIL Sosick Motorsports

    R.I.P. Christopher "CRAZY CHRIS" Beckmann
    "you dont appreciate friendship until you lose your bestfriend...."
    I'd rather have the knowledge and ability to do it than the money to buy it already done.

  5. #5
    Does the car idle more poorly when just turning on the AC without braking?

  6. #6
    You are here entirely tooo much!! Stewi's Avatar
    Join Date
    It sounds like my car about a year ago. My problem was the alternator was on its last legs and once I turned the heat blower on it drew too much power and the engine RPM would drop significantly, if I was stopped, I had to give it a little throttle or else it would stall. The other problem is your idle itself might be too low, try adjusting the idle screw on the throttle body and raise the ide 100-200 RPMs. Whats your idle at right now with nothing turned on except the engine?
    Quote Originally Posted by qnz
    well there are talkers and there are do'ers. talkers never do. and do'ers never talk
    99' Galant ES

  7. #7
    I have the same problem when i change my battery, it stalls when i idle. what i do is i disconnect the battery for about 30 mins, then reconnect the battery.

    this time when I installed a new battery, I did the same to get rid of the stalling. But now, the engine dies when I turn the AC on. Even if i rev the engine to 3000, I turn the A/C on and the engine dies. What's causing this? How can i fix this? My A/c had no problems before I changed the battery.

    if the car is moving and i turn the A/C on, the engine dies. my idling w/out A/C is normal.

  8. #8
    anyone thinking an IAC valve? this sounds eerily similar to what i had. when i would turn the AC on at idle the car would drop massive idle and then go into a stall.

  9. #9
    i can't stand it anymore, so i went to a mechanic. He cleaned the throttle and now it's ok. he said GM cars usually have this problem and that cleaning the throtle usually works.

  10. #10
    Hello all!
    I understand this to be an older post however, just started to experience the same issue with vehicle (02 Galant ES V6), having rough idle and eventually stalled while stopped in Drive (when AC is on MAX and rear defrost is on at the same time).
    I removed and cleaned IAC valve located below throttle body, attached by three Phillips screws (see following link below for procedure), and did not resolve issue. Also cleaned throttle body. I did notice an odorless almost vapor like smoke coming from vents when AC is on. Does not smell like antifreeze, oil etc. Perhaps heater core is going bad?
    Anyway, confirmed that compressor clutch becomes engaged and radiator fans turn on when AC is on. No screeching or apparent belt slip is noticed. Could it be possible that compressor relay is going bad(although am receiving cold air)? Notice car stalling more so when rear defroster is turned on while AC is in use. When rear defrost is off, AC behaves normal and vehicle does not stall.
    Any additional information or possibilities that may be causing issue is appreciated, thanks!

    2001 Mitsubishi eclipse GT 3.0 Throttly body, IAC and MAF sensor cleaning;

  11. #11
    TGC Lifetime Patron oakrdrs187's Avatar
    Join Date
    Coachella, CA
    If the battery was recently disconnected it's still relearning shift points and lowest maintainable idle.

    If not, the battery and alternator are next. If the ac clitch is engaged putting added load on the engine along with
    The max speed blower motor, both radiator fans constantly running along with the defroster simultaneously are big electrical strain which if these aforementioned parts are not in good shape will cause stalling.

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