Something wrong with w126 climate control system?

[84MB500SEL]

Idk what exactly is wrong with the system, but I'll describe several problems with it that I experience- they may be related? First, with the three sliding switches directly under the front center vents: the one on the left seems to not do anything- whats it supposed to do? the one on the right also seems to not do anything- is it supposed to open a door in the air system, because it doesnt seem to affect the airflow in any of the vents- maybe both the left and right switches are broken? Only the switch in the center works- it controls air flow in the center vents- when its closed no air, but when open, fresh air always blows in, even in the winter when it's on recirc and I want only heat to blow in through the vent. The passenger side front air vent always has air coming out when the blower is on- no switch can stop the air flow. The driver side air vent never blows air out- no switch can turn that one on. Also, a smell of gasoline seems to be coming in somewhere through these vents- idk where from. I don't think there's anything wrong with the climate control electric module, but if this makes any difference, only when I turn the climate temp switches for the driver and passenger sides to below max heat, when I'm driving, sometimes it sounds like the blower motor or something around the glove compartment makes a buzzing noise, but it never does this when the temps are switched to max heat. Is there a fresh air door that's jammed or something? Is there a network of air flow tubes that has messed up doors (either stuck closed or open) or something? Does anyone have a diagram of the w126 cabin air system? Can you tell me any more info about this complex air flow system so that I can take it apart and fix the problem? Thanks.