I have a 2006 chevy malibu that when i turn off the car it keeps blowing air. This started last week, along with that while trying to change fan speads
You can pull the fuse to keep the blower from running down the battery while you work on the problem, which is either a bad ignition switch or a short circuit somewhere in the blower motor, switches, or associated wiring. Your mention of another problem with the fan switch is not clear, but that would be a logical place to start.
There is a “fan speed controller” in the plenum that would most likely be the problem.
Maybe this car is working as designed, what I mean is I installed alot of GM “afterblow” kits that kept the blower going and the bacterial growth on the evaporator down. They time-out after 30 min though.
Ignore that last post. Apparently the 2006 Malibu does not have the “speed controller”