When the a/c cyles on my 2001 Civic the engine seems to shudder. Why?
There is an electromagnetic clutch on the compressor which puts a load on the engine when it engages. It’s more noticeable with 4 cylinder engines. My Accord will sometimes actually creep forward a few inches when the a/c cycles.
The computer should bump up the idle speed when the A/C is activated to handle the additional load. You may have other issues, like needing a tune-up or a good throttle body cleaning if the engine shudders or stumbles when the A/C comes on.