[Chicken]

As title states, a 2004 Grand Marquis GS with 101,110 miles. Everything is in great, working order and the AC system works as it's supposed to.

Does it also affect your CV, GM, or Towncars the same way? Whenever it's on setting 3/4 or full blast and the compressor is running strongly, the engine power is reduced noticeably. Just more sluggish, not as much torque response. On half blast, it's closer to normal, and the moment you stop the AC, it's normal again. I wouldn't have thought that AC could sap so much power in such a big engine. In my dad's Corolla, it can be in full blast and it's hardly noticeable.

 

[R.S.LOGAN]

Happens with a lot of cars , especially more noticeable on smaller engines . You could check your alternator under load and see what it's charging at . Also check your battery voltage / condition when left overnight .