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Hello Folks…hope you can help. My daughters Pontiac Vibe stalls when in drive or reverse when the AC is on max. In park it is fine. Parts that have been replaced recently: Rad and fan, coils and plugs, fuel injectors, ignition switch, MAF sensor and air filter and PCV valve. I cleaned the throttle body 3 times and did the idle relearn. There is no IAC to clean or replace. I checked for vacuum leaks and didn’t find any. Alternator puts out 13.34 volts at idle. I’m at a dead end….any help would be appreciated. Thank you.

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  • If this car has no IAC valve, then it would have some other mechanism to up the idle when the compressor is commanded on. Some are vacuum operated. I don't know much about them, but you might want to look around at the throttle body and see if there's some other type of valve that would increase throttle if needed.
    – Jupiter
    Jul 1, 2021 at 18:58
  • @Jupiter - Most likely the vehicle is drive by wire (DBW), which means it wouldn't have an IAC and the computer controls the throttle body itself to gain RPM (just checked, it does appear to be DBW). Jul 1, 2021 at 22:10
  • Yes…it’s DBW. The hvac fan has 5 speeds, 0 is off and 4 is the highest. The car idles ok when the the AC is on and I set the fan to 1,2 or 3. As soon as I put it to 4, the rpms drop and it stalls, but only when it’s in gear. If it’s in park, it has no effect.
    – Iggy1969
    Jul 2, 2021 at 0:47

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