I have a 04 Grand Marquis with 75000 miles I also
a rattling noise in my engine when I turn on the
A.C. and drive what could it be
The AC clutch is most likely the problem rattling, replacement time.
Check as stated above the A/C clutch followed by the serpentine belt tensioner and idlers.
Okay I know what the serpentine belt are but what are tensioner and idlers
Tensioner is a spring loaded belt pulley that keeps tension on the belt. Idler is a belt pulley that the belt runs on. You should have someone look at it for you.
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