trund

Hello Forum,

What are the probable causes to test for??
My wiring harness plastic plug at the blower motor is burning out. Replaced twice.
The plug on the other side of the harness, the one that goes into the resistor, is fine.

See photo.

Thanks guys.

Note the burn out on the right side, black wire.

mountainmanjoe

Blower motor is worn out and causing high current. Possibly coupled with a corroded socket.

trund

Mountainmanjoe,

Is it possible to open the blower motor and look (and sniff) around for a short, check the windings, etc.?

Ted

mountainmanjoe

What usually happens is the oilite bushing run dry. 10 years of life sounds about right. When you turn the blower on, there's too much static friction. The armature doesn't start turning (until you smack the motor with a hammer), and after the field saturates you basically have a dead short through the commutator bar. Or it may work intermittently. Since there's no changing inductance to limit current when this happens, you now have continuous full short circuit current going through the motor circuit, which stresses the resistors (consequently that usually burns them out too) and any connections with a higher resistance (like your plug there).

The motors are not user serviceable. They're sealed units stamped shut, meaning you have to destroy them to disassemble. And it's not worth the effort to try. They're optimised to be disposable products. By then the damage is done, and attempts to revive it may squeeze out few months of life. Most people would rather pay the $30 to just replace it with a brand new one and get 10 more years of reliable service.

trund

Thanks, mountainjoe.

You are an encyclopedia.
I'll buy a new motor.

Ted

mountainmanjoe

I've been through it