Air Cond. Problem

First time using this.......so bear with me please. I have a 1997 Trailblazer and the check engine light came on. The next day the air cond. stopped working......it will not blow air out of the vents, but I can hear air blowing . The rear air works fine though. Do you have ANY idea what would cause this? I would really like to try to fix myself before spending a ton of money, and was in the process of trying to sell. (how conveninant it would happen when it did) 

First thing's first, they did not build a trailblazer in 1997.  Second, the first OR second generation s/t utilitys did not have a rear blower.  I will assume that you have a 2002 or newer Trailblazer (3rd generation s/t utility) and also that it is an EXT model, because they are the ONLY s/t trucks EVER built with a rear a/c unit.  You need to first check and make sure the compressor clutch is engauging when you request a/c operation.  It should be if the rear unit is cold.  If so, you probably have a restricted orifice tube, that's about the only thing that can cause the front a/c to blow warm and the rear cold, except a temerature door not switching to the cold side.