Radiator could be clogged.  Thermostat could be stuck closed (or partially closed).  A hose could be soft and vacuuming closed.  Anything that could cause overheating under any circumstance could be suspect.

---- John Rodgers <jrodgers113@GMAIL.COM> wrote:
> Please reply by P-mail
>
> Trying to help my son. He has 2000 Ford Ranger, 4WD, 4 L V6, and it
> overheats every time the AC is turned on. Everything seems to be up to
> snuff! Any ideas as to the problem?
>
> Thank's,
>
> John

--
David McNeely