My car idles funny but only when I turn the AC on. This only happens when I'm not driving , only when I'm stopped at a red light or something like it . Once the AC turns off it goes back to normal

 

Normal to an extent. If your idle is real rough, then it may be two possibilities. One, the solenoid that kicks up the idle a little when the compressor is engaged is not working. Two, your compressor may be dragging the idle down which may be a sign that its failing.