Rough Idle When the Air Conditioning is On.

Hello, the air conditioning system will definitely add a load to the engine, causing it to lag or bog down slightly. If it's excessive, at idle, it could be that there is an engine performance problem or maintenance needed, such as spark plug replacement or ignition component service needed. This is all a guess, and hands on assessment of the system should happen. The air conditioning compressor, also, could be a concern, causing extra power to turn due to internal concerns. This can cause excessive drag on the engine when it runs. Lastly for consideration - your engine mounts could be worn to the point that they allow the engine to vibrate excessively and be more noticeable than usual. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops