OK, a while back, i was tuning a friends car and we hooked a wide band up to it. the a/f was 13.5 being 90 degrees outside, we turned the a/c on and the a/f dropped to 12.5.
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i got back to my place and tried it out on my car (different wideband) and the same thing happened. i got a .7 lower a/f ratio with the a/c running. SO a few days later, another friend of mine tried the same thing. he never noticed it but it did the exact same thing. got a .8 lower a/f ratio with the air conditioner running.
im guessing that the a/c kicks more fuel to the motor because it bogs the engine down so much. what do you guys think???
All I know is that when I used to drive a Cav 2200 you could feel the A/C slow the engine down EVEN more, if thats possible.
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Words that you can't use in modding: Finished, Perfect, Cheap.
the compuer has to adjust for the load of the a/c , so the pcm riching up the mixture , sounds about right
its like tuning with your hvac knobs
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Kick azz is my boost hero!!! 
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the engine has more strain on it so even with the minute gain in AFR its still going to make less power
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1989 Turbo Trans Am #82, 2007 Cobalt SS G85
that would be exactly my response. the load from the a/c on is causing the PCM to adjust the mixture. so in this case looks like you have 2 options: 1, turn the a/c off, or 2, turn up the boost if your a/c is on.
I was a retard, and now I'm permanently banned.