Cadillac Repair: AC Troubleshooting, cadillac deville concours, small screws

Question
I have a 1997 Cadillac Deville Concours DeElligance.  My AC is blowing nice and cold out of the passenger vents, but it is blowing warm air out of the Drivers vents.  Occaisionally the drivers vents will blow cold, but for short periods, then back to warm.  I have tried changing the settings from auto and I have tried selecting different vents with no luck.  Have you ever seen this and if so, what could be causing this?

Answer
Hi,Dwayne

Yes this is a common problem,it is usually caused by a mode acuator,if its the drivers side that is the main concern then it is the drivers mix door acuator that is failing and would need to be replaced,the acuator is located at the left center of the dash at the heater box,it looks like a black rounded module that has a cam in the center,it has a connector with 4 small wires,2 small screws hold it in place,the part can be purchased from Cadillac parts only.

ED