Amer

Car is fully stock, the problem is a slight vibration (but strong enough that I feel my seat shaking) when my A/C is on and car is idling normally. When I turn off the A/C the vibration is gone. Anyone else experience this?

xviper

Turning ON the A/C causes the clutch on the compressor to engage and thus, allows the belt and pulley to turn the internal shaft and mechanism of the compressor. I would suggest that you check the compressor more closely, BUT with EXTREME CARE! Don't get any fingers or loose clothing get caught in the belt and maybe have someone with you for an emergency engine shut down. If this vibration is from the compressor, you should be able to carefully observe (or even place a stick on the body of the compressor as your assistant pushes the A/C button ON, then OFF. You may be looking at a compressor rebuild.

Slows2k

Worn or broken engine mounts, Something bent from a wreck and touching the engine, AC system overcharged with refrigerant all can cause a vibration with the AC on.

Any work done to the AC or previous accident damage?

What is the idle speed with the AC on? Too low of an idle speed will magnify the vibration from the AC running.

Slows2k

BTW, There isn't anything inside a AC compressor that can be serviced. The Clutch and field coil can be replaced, but they won't cause a vibration.

xviper

If the clutch is grabbing and slipping intermittently, could this cause a vibration from making the belt tensioner work overtime?

Slows2k

I guess it's possible, But I've never seen an AC clutch do that.

xviper

Not on any modern day car, but I've seen where the pulley didn't turn freely through 360 degrees. It had a "tightness" in one spot. Every time the pulley got to that point, it required a lot more force to turn past it.

Amer

Thanks for the response guys. Should I just take it to honda and tell them to inspect the motor mounts and ac compressor?

To answer some of the questions, car has a clean title never in accident and the vibration occurs at idle 800-900 rpms with A/C on.

xviper

A little more detail:

Is this vibration constant as long as the A/C is on and engine is at idle or does it just "stumble" a little as you turn it on then goes away as the A/C continues to run?

Amer

When car is in idle and A/C is not on, no vibration. I tap up on the fan setting to 1 green light then the vibration starts and never goes away. Just for a background, I had a CEL 4 months ago for misfiring, the dealership tried fixed this by replacing the spark plugs, doing a valve adjustment, and the real resolution was replacing coils.