Heat problem?????

The fan is off, an dthe temp guage is all the way down, But i'm still getting heat inside.. I have to keep it down on the floor, or it gets unbareable on these 90 degree days.. What causes this, it just started this 2 weeks ago.... What do I need to do... any help will be gratly appreciated... This is on a 1999 jimmy XLT:banghead:

Auto matic or manual AC control?
Does the AC put out any cold air?
Does it switch from floor to vent and defrost right?
Does tempt control change the heat output any?
First
Check fuses and engine vacuum to heater controls.