when i turn on my a/c i can feel the car vibrate and when i turn it off it returns to normal. if im in motion, i cant and dont notice the change in vibrations but if im at a standstill my car begins and continues to vibrate more than normal until i turn it off. as soon as its off, the vibrations stop. what do i do? it still blows cold and doesnt blink ever. thanks guys!
Turning on A/C makes my car shake - 6G Celicas Forums
mine does it too, I think air conditioners take a bit of power when on and make your car slower so shaking on idle may be normal.
The A/C drains alot out of your car, if its little vibration its normal.
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i know that when u turn on your A/C, it is supposed to adjust your car's idle accordingly in order to counter the stress the A/c puts on your engine. But i still dont know which vacuum line does it and how it control it , so my car shakes as well 
Check you AC idle up. can't get onto bgb again for some reason, so I can't tell you 100% what to do. The A/C idle up is a VSV AFAIK, and is located against the firewall, by the diagnostic box. Check the vac lines running to/from there, and try adjusting the screw on it.
on my ST the AC idle up valve is on the firewall right behind the intake manifold.
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