So, my 96 98 was blowing tepid air out the driver's vents and frigid air out the passenger's vents last week when I had the heat set to full blast. I found this thread on a Buick forum:

https://buickforums.com/forums/threa...ctuator.15234/

I replaced the blend door actuator behind the glovebox and it fixed the problem. Unfortunately, my dual zone climate control has never worked right. I'm not sure if it's the temperature select switch on the passenger's door or something else. You can have the AC set to Auto or manual and when you change the temperature on the passenger's door the "PASSenger" light illuminates on the AC control head. Even though the PASS light turns on the temperature never changes on the passenger's side. Has anyone experienced this on their C/H body Buick, Pontiac or Oldsmobile? Any troubleshooting advice?

Thanks