Looks like that voltage reducer cost twice (or 3x) the price of a 12V motor. If the ground isn't the solution just buy the right motor instead of another voltage reducer. Or a cheap resistor as Jerry suggested.

Info on heater motors
https://www.stovebolt.com/ubbthread...6055/Easy/cheap_heater_blower_motor.html


1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-