blower motor (I searched)

since I got my car last november, my blower motor work only on high. I check my resistor it's pretty corroded, I tried cleaning it a bit and testing w voltmeter all the circuits seem ok. could it still be bad??
another thing, I ran my fan with out it, and it would still run only on high, is this normal? or is it supposed to run on all speed with out it hooked up?? thank for any help..
 
I would be lookin at a bad resistor-pack for the HVAC motor. It seems to me that the motor gets full power and when you use lesser fan settings, juice goes through the resistors to cut the fan RPM down. If the resistors are bad, only high works (which gets full juice).

Good luck.