I get good cold air out of the passenger side vents in my 98 STS. The drivers side vents have much warmer air from inside of car comming out. . . Turning down temp on drivers side makes no difference. I suspect some kind of flapper door problem inside the ducts some place.

 

You may find this hard to believe, but this is a very common symptom of low refrigerant.
If the system has a full charge(2 lbs) and the problem remains, then a relearn of the mode door actuators would be next.
A tech 2 is the only tool i know of capable of this procedure.

 

Thanks very much. I'll check out the refrigerant charge and let you know.
Appreciate the info.
Bob

 

That did the trick. By the time I got 10 oz. of freon in it, the Drivers side was putting out air below 40 degrees. I put the rest of the 12 oz. can in. It's running great now.
Thanks for the tip.
bob