The car vibrates when the A/C is on?

Hi,

Does this only happen when the engine is at idle speed (in gear or park)? I ask because it sounds like the engine idle speed may be too low.

The engine's idle speed is controlled by an idle speed control valve. The engine's RPMs are viewed by the PCM. The PCM then tells the control valve to either allow more air or less air to the engine to control the speed.

When you turn on the AC, there is a load placed on the engine from the compressor. At that point, the control valve should allow additional air to enter to compensate for the added load. If it doesn't, the RPMs get low, and you feel a vibration.

What I would recommend (if this only happens at idle) is to service the idle speed control valve.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/idle-air-control-valve-service

If this doesn't help, the component may need to be replaced. I attached pics below and the directions for replacing the valve. Note: This is the only way I have the directions for the removal. Take a look through these things and let me know if you have questions.

Take care,

Joe

See pics below.