AC blows wrong

1994 S15 GMC Jimmy-air conditioner blows cold air but it all comes out the defrost or the heater ports, no matter where you put the switch.

Look underhood at the vacuum ball reservoir that is mounted to the hood- See if the rubber vacuum hose has come unplugged from the ball- this is usually what is wrong when as you have described your situation.....

only vacum ball is next to engine coolant reservoir, one hose on it. nothing is mounted on the hood but the light.

Check vacuum lines from engine to heater controls.
Also make sure it uses one or two hoses on vacuum ball.
MT