I have a low humming vibration that oscilates in the cabin when the car is in neutral and the AC on, it goes away when I turn off the AC
I have checked my motor mounts and they look fine and there is nothing rubbing the frame or anything....has anyone run into something like this?

 

there might be a bad ground somewhere

 

Yeh I Have A Similar Problem Im Thinking I May Need To Change My Belts...how Bad R Ur Belts?

 

I believe that is probably just the AC compressor running. It happens on all cars.

 

It doesn't happen to me. I used to have a problem like if i had my AC on and i turned on my rear defrost.. the car would act like its about to stall.. but i changed my battery and fixed the problem.

When i turn my AC on , the rpm goes up a bit and fan comes on, other then that no vibrations. Maybe its your battery?

 

I think I know what you are talking about. In fact, I've been to the dealer twice and was told they could not duplicate the fault. I always feel an irregular, oscillating vibration when at idle. Sometimes it kicks stronger than others, and usually is more noticable with the AC compressor running. If you open up your hood with the engine running and watch it closely you can even see the block make these little jumps. Just put your hand on the engine cover and feel them.
The bad news is that I've come to the conclusion that this isn't really a "problem." Annoying as it may be, it seems to be common to many V6 vehicles. My folks own an xterra with the V6 and its jostling engine is much worse than what I feel in my 02. Another example is my friend's 01 Accord V6. With about 60k miles, I feel a vibration in his car that is different in character but still similiar to our own. Lastly, I've sat in two other Maximas (01 and 02) and both of them exhibited this behavior. It seemed to be less pronounced in those 2 vehicles, but they both have low miles.
You may just have to learn to live with it. I gave up trying to fix it a long time ago. Still, I'm very curious about what the root cause is. I've heard people say that the peculiar firing order and balance techniques used to make a V6 feasable can only eliminate so much of the oscillating behavior in that engine confiiguration. As a result, minor perturbations in the combustion chamber will be felt worse than in an engine with cylinders in multiples of four. It sounds convincing, but I really don't know enough about this stuff to be confident. Maybe someone here with more technical knowledge could break it down for us.

 

Well, definitely some good input.
- Havent tested a grounding problem, so will have to do that
- Belts look fine, no cracks or glazing (no squeaks)
- Batt and Alt are healthy with +12v consistent

Rizzob brings up some interesting points. I thought these cars had idle management that would raise the idle RPM when the AC was on. I know every car that idles lower than usual will vibrate, but I find it difficult to believe that its normal. We also have a lexus RX330 and when I sit in it with AC on, i cant even tell if the darn thing is running! and thats a V6.

I will do some more hunting, but like you said I might have to deal with it and compensate with louder muzak!!!

Thanks all

 

My RPM rises when the compressor kicks in. Heck, sometimes, the RPM sits steady after the compressor kicks in. The car is quiet and all you hear are the fans running from the outside.