RPMs dipping when turning on the A/C?

Hi,

The idle speed is controlled by the PCM. The PCM identifies the engine load and adjusts the throttle valve to maintain between 650 and 750 RPMs.

If you only experience this when the A/C is on, there could be excessive drag from the compressor, which is unlikely. However, I need you to try a few things. First, start the vehicle and place it in drive or reverse with the AC off. When you shift to a gear, does the idle speed maintain the aforementioned RPMs? If so, while in gear, turn on as many electrical components as you can but not the A/C. Additionally, turn the steering back and forth. Does the idle drop then?

If the things above don't affect the idle speed, the next concern is the A/C compressor is under too much of a load (over-charged or too much PAG oil). I don't know if you have serviced it recently. If the above tests do lower it below 650, we need to start checking for engine vacuum leaks.

Here is a link that explains how to check:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, I need you to have a helper turn the A/C on and off while you listen to the compressor engage and disengage. Does it make excessive noise or sound odd in any way?

Let me know.

Joe

Hi,

Thanks for the update. I'm glad you got it taken care of. Please feel free to come back anytime in the future.

Take care,

Joe