Just a quick note as well, when you bench test the blower motor, it should VIOLENTLY spin hard and fast enough to jump out of your hand when applying 12v directly. If it gently spins up, the motor is probably shot.

Mine spun gently and quietly and seemed ok until I got a good one to compare to. Night and day difference, you can barely hold onto a good motor with two hands while running.

The reason to ground the blu wire in situ is so you do not have to take the blower out to bench test.
We do it right where it sits and I use an amp meter to verify draw at the same time.

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A Dalton