Vibration with a/c on...

[ChilinMichael]

So here we go,

Little history behind this beforehand to help diagnosis. New A/C about 6 months ago, it wasn't used much because before that, the airmix actuator went out and there was no sense to me in keeping it on and losing fuel economy, so I always shut it off. Just last week airmix actuator got replaced and HVAC is fully functional again (minus recirculation mode, but that's another separate issue). Car has new all new ACDelco Fuel Pressure Regulator, PCV, IAC, Spark Plug Wires, and NGK TR55 plugs. The car's idle was messed up before this tune up, but now beyond perfect. Although, now when the A/C is on (which it doesn't make a BIT of noise and works perfectly) the car tends to vibrate at idle, and especially when you are taking off at the slowest possible speed from a stop. The car vibrates enough you can feel it in the pedal and almost feels like it's resisting you. Is this normal? Funny thing, I don't remember my old A/C (before the clutch blew to bits) doing this to the car. The idle seems to stay at the same RPM whether the A/C is on or off.

Ideas?

[1fatcat]

How are your motor mounts?

[rharper]

How are your motor mounts?

just what i was thinking

[repinS]

I sometimes get this from my high speed fans, which do come on with the A/C. I don't have a compressor (just an idler pulley) and a switched fan override, so reproducing it is easy and it's definitely the fans.

[ChilinMichael]

Yeah except this happens with the motor and varies with RPM...I think I can safely rule out the fans.

[ChilinMichael]

Update: Found that a transmission mount on the passenger side is bent and the bushing is about to fall out, it's being replaced late this week or early next. Will see what happens once that is done....though there has been NO issue since because the car hasn't gotten super-hot, that one day it happened it was 78 out and I was in stop-and-go traffic so it's hard to recreate that now...

I'm sure my "spirited" driving bent that mount...