Toyota Repair: 1995 Corolla heater fan failure, squirrel cage fan, auto salvage yard


Question
My beloved Toyota Corolla just turned over 172,000 miles. But in the hottest week of the year (so far) the blower fan has failed.  I used a rubber mallet to rap on the bottom of the blower motor, and it started running again, for one more day.

I've removed the glove box and dismantled the motor from the housing, and now I'm left with just the motor and the squirrel cage. CAREFULLY plugging in the motor and turning on the slide switch results in the fan coming to almost instant speed, unless I turn is right side up (as it is installed)...when it immediately stalls and coasts to a dead stop.

What causes this?  I'm going to get another used one from the local used auto salvage yard, but I attempted to clean up the squirrel cage fan, and found it coated with not just dust or greasy dust in the blades... but when I pulled it off the shaft, inside the fan is this AWFUL dried "lamp black" coating every surface.  Any clue what it is, or how bad this is?  

Can I expect my next blower motor to go the same way? How many miles are these fans supposed to last, anyway?

Answer
Usually the blower motor lask over 400, 000 km. how many hours it could run ?! I have no idea.
My suggest is take a set of jump wire with you, when you get another blower motor, test it by feed power with your car's battery. A good blower motor should running quitely and smoothly.