91 Caprice blower motor

[vdorobantu]

I seem to be having a problem with the blower motor on my 91 chevy caprice. Lets say i drive the car, then, i park, turn off the engine, and do whatever i need to do. When i come back to the car, i would find the fan blowing at full blast (3rd speed). Whenever i exit the car, i specifically turn the lever to off, and the fan level to low. The most frustrating is in the winter, because i go to work, and when i return, my windshield is one big frosty and it takes me 1 full hour to defrost it completely, not to mention the marks it leaves on the inside. A little info on the car 91 chevy caprice, 305 5.0L(L03), power windows, rear defrost, delay wipers, with AC, analog climate control. I need to find out what this is because its making me...angry. I have changed a few engines and solved a few dillemmas by myself(i work as an auto mech apprentice), so i don`t mind getting dirty all the way. Thanks.