97 Tahoe A/C Not Cold

My 97 Tahoe has front and rear air. The rear air is cold as ever. The front however is not. Even with them running at the same time the rear gets cold and the front is the same temp. as outside. I checked the sstem and the compressor is fine. I believe my problem is in the drier. It does not get cold (normally where all the condensation comes from under the hood). The a/c line splits ( in a "Y") just before it connects to the drier and the line is very cols except for where it enters the drier. the other side goes to the rear and is very cold as well. I am assumning there is a problem with the drier. HOW??? There is some pressure switch on the side of the drier I have already replaced... didn't work. Please help, it's beginning to get very HOT here in Houston, TX.