2012 Sonic blower motor not working?

I have a 2012 sonic, recently purchased. The
blower motor quit recently, turn the knob to any
setting, nothing. Here's the thing though, about 20
minutes down the road, it'll cut on for
approximately a minute or so then it'll die again.
40a fuse is good, ohmed it out and it's fine. I
checked voltage at the motor itself and it's getting
11.95v, but it didn't change from low to high speed.
Tapped and smacked the motor, still didn't turn on.
Ordered a new resistor and secondhand blower
motor, installed the new resistor and now the
voltage does seem to follow fan speed but both
motors don't turn when plugged in. I know it's
possible I just found myself with 2 bad motors but
is there anything else I might be missing? Its 30
degrees here and I have a 45 minute commute, I'm
ready for my heat to be back!