johnnyhawthorn

I have a 1970 Cultass Supreme convertible with A/C. When the blower motor is set to high speed, it pops the in-line circuit breaker. This would indicate to me that there is a short in the blower motor. The blower motor relay was replaced and checks out OK. From looking at the diagram of the blower motor circuit, there blower motor relay is the only thing in-between the blower motor and the horn relay when it is set to run at high speed. I'll put this out to the forum for suggestions on what to test/replace.

Octania

That's one possible cause.
Faulty relay is another.
What say you measure the current draw?
I imagine the blower motor is a permanent magnet type? [Could be wound stator instead] If the magnets are weak, the motor will draw excess current but have reduced output. Or, the armature / brushes may be defective. In any event, if the motor is drawing excess current, replacement is the answer.

BILL DEMMER

check your high speed blower wiring for chafing. check the relay connector for melted plastic(common).
lubricate the bushings of the motor.
the bushings may be worn. i've seen a blower still run with the shaft worn through the back bushing and case.
you may have a partially shorted armature. one thing that can cause this is not having the blower bypass hose connected, which will cause the armature to overheat, burning the insulation from the windings.
i highly doubt there is a problem with the permanent magnets inside the motor.


bill

MDchanic

Bill's got all the bases covered. My money's on tight bearings or a missing cooling tube.

- Eric

jag1886

When I work on cars that usually meant the blower motor was on it's out.