I have a 2002 Dodge Caravan with 81,000 miles. Several times after highway driving for a few hours will get noise from power steering pump and straining noise when turning. The steering never locks up. After sitting for a half hour no problems until again 2 to 2 1/2 hours of driving. Had serpentine belt and tensioner replaced after first incident, thought belt might be slipping when warm, but just did it again the other day. No problems with daily driving on short commute or less than several hours of driving. Was told about a year ago rack was leaking, put conditioner in reservoir and have not lost fluid or seen leak in driveway. A friend feels power steering fluid may just need changed. Any advise?

From the sounds of it you probably have a power steering reservoir clogging up I would try
A local dealer to have it flushed. If that doesn't work then you may need to have it replaced

We Have the same problem and it's a problem on every 02 caravan. We just deal with it and never had it fixed. Our van has 120'000 miles on it and its made noise as long as we owned it for the last 5 years