Defogger problems of the 2002 Chevrolet S10

This vehicle has had a problem with the defroster that began at under 20,000 miles. The dealer has attempted repairs twice under warranty. As I am once again having the problem, and off of the warranty, I began looking on the internet for information. It turns out that the transfer case vacuum switch goes bad and allows the fluid in the transfer case to be drawn up into the hvac system. This causes, among other problems, the defroster to not operate. This is a very difficult and expensive problem to correct as the entire hvac system must be flushed out and any bad parts replaced. This seems to be fairly common and yet gm will do nothing off warranty, and in my case did not correct the problem under warranty. I believe a recall is in order.