There are no resistors for speed on 124.032 chassis. The speed is controlled
on these via the Control panel sending a variable voltage signal [ 3v. to 7v.]
to a transistorized voltage regulator/heat sink
with a switched ground next to the blower motor.
The test is for voltage at the 3 prong plug behind the brake booster. The
yellow is trigger volts and the others are load power.
I would check the main feed fuse /circuit