There are two main possibilities: the blower motor resistor is failing/has failed, or the blower motor itself is failing/has failed. Most likely it is the blower-motor resistor, they are well-known to fail. Sometimes they fail in such a way the fan only works on high, but no lower speeds; sometimes they fail totally. Mine went out about a year-and-a-half ago.
The resistor is usually less than $45.00, even at the dealership. They say you can change it yourself, if you can get into small areas. I had the dealer do it and I was out the door for around $150.00, I think. One of the few repairs I have had the dealership handle because I could not seem to wedge my self under the dash board on he passenger's side of the car. Several of the folks on this site have done the job themselves, succesfully.
If you want to tackle it yourself, there is a free, complete 2002 Factory Servce Manual you can download that shows you where it is, and how to do it. Even if your vehicle is not '02, the ac system is pretty much the same on all second generation year models ('99-'04). They may even be the same as on the first generations, I don't know because I haven't worked on any first generation Intrepids.
And if it is the blower motor, that is pretty easy to change, too. Providing you can get into the area. I'm pretty sure both these items are sold at auto-parts stores as well as the dealership, they won't be Chrysler-made items.
The fan switch is not working. Well, intermittently. The A/C green light on the button comes on even when the fan switch is off. The compressor kicks in but the fan doesn't blow. Something easy I hope.