2007 Pacifica makes a much louder than a normal noise after using Heater
 

I am having trouble locating this noise after a trip of more than 20 miles and after I have had to use the heater and defrost. The noise does not start right away but waits until the end of my trip, usually while I am stopped for an extended time, i.e. drive thru window. This noise is not your typical Squeal, like if it was from the A/C. It's much rougher and louder. It seems to come on while the fan kicks in but the engine temp is at normal. Puzzled and need assistance?

I had something like that, it was one of my cooling fans. the blade assy was moving, because it was starting to come apart. you can unplug one, or watch them when they come on. mine was intermittent at first then got worse.

Thank you gbeach. So when you disconnected one of them. How did it affect the performance of the car or did you have to replace the whole dual fan and radiator package? Or just one of the fans?

I disconnected the fan I knew was bad til I could get the fan assy, because I was scared it would take out the radiator. you can disconnect one fan, and your car won't overheat.
when you replace it comes as an assy with both fans. it was really easy and I got mine at rockauto. but again, I knew it was the fan, I watched the blades when it kicked on and it was easy to see. not saying that is what your problem is. I would watch them when they kick on, and disconnect only one to try and see if that is even your problem if it is doing it quickly.