good chance your blend door actuators took a dump on you.

here's the write up to change them. http://www.grandprixforums.net/blend...ent-21941.html if you take the glove box off and with the car running change the temp on the climate control and watch the little hole in the actuator to see if it moves at all.

you can also grab each heater hose to see if they are both hot, if so, the core is flowing.

or your climate control has died, or the outside temp sensors not working right.