rear a/c on 1997 GMC Savana 1500

i have a 1997 gmc savanna 1500 5.0l v8. the front air is working fine but the rear air is blowing out hot air. i check the fuse and it was OK. is there a fuse somewhere just for the rear i don't know about, or could there be another problem?

Asked by for the 1997 GMC Savana 1500