this has been going on for quite a while, but only recently since it started raining again and i have to keep the windows clear, has it become ANNOYING.
my problem is this: the a/c works fine, as long as i'm not sitting idling. if i'm at idle, and the compressor clicks on, i get this HORRIBLE booty shaking shuddering lumpy idle that jumps up to where the engine should run with the compressor on, and then suddenly drops to where the engine almost stalls...car shudders hard, engine vibrates enough to knock the intake against the hood, lights dim, etc., then it jumps back up again. up, down, up, down, up, down, shake shake shake, until the light turns green.
then once you start moving again, serene smoothness.
it started doing this after an ECU reset in november or december, and the only breathing mods were intake and exhaust. any ideas at all?