1993 740iL Heat/AC vent issue

Hi all,

My name is Todd and I am new to the forum so forgive any mistakes or if my issue is a repeat. I have a 1993 BMW 740iL. Here is my issue:
With the temp set at the max for both the passenger and driver I only get hot air from the vents on the drivers side, on the floor, dash and even underneath the seat vent. I can only get cool air from all the passenger side vents incl. the center rear seat vents. With the AC on I get cold air from all vents except the vent underneath the drivers seat vent.
As an FYI when I start the car I hear what sounds like some type of slides in the vent system moving??
I have replaced the thermostat and have tried all the settings available. Any help or insight would be appreciated.

Thanks in advance.

i had the same issue w my 93... GL. hopefully someone can help both of us