Air Conditioning

Help! My air conditioner will only blow hot air. It's a 96 Bonneville with the electronic air/heat control. Any ideas anyone?

More info , has it been serviced? is there freon in it ?

No service to the air conditioning, the last service the car has had was the ignitioin switch was replaced. The charge is in the green zone on my gas gage. It's the electronic control and no matter how low you set the temp. it blows nothing but hot air.

If your a/c is working properly up to the vent is is most likely air mix actuator sticking and not opening the door flap.Take your glove comp apart and look for the arm moving back and forth, see if it is moving smoothly when you turn temp up and down.Shows here what to look for courtesy JRS 3800 .
http://smg.photobucket.com/albums/v294/Jr3800/95%20Misc/?action=view&current=actuatorWoes.flv