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I've been told that heater blower motors will reverse direction when the polarity is swapped.
Modern permanent magnet motors will reverse direction with polarity but the heater motors Packard used have a separate field coil and armature which are permanently connected together internally. Unlike the permanent magnet motors which have the N-S relation of the field always the same, if the polarity is swapped the armature reverses direction because only its N-S changes and changes the relationship between field and armature. On the older Packard motors because the windings are connected together, the field coil swaps N-S as does the armature so the N-S relation between the two stays the same and the motor keeps running in the same direction. Same applies with the starter motor.
Packard used two methods to reverse their motors One was to bring field and armature out as separate leads and change orientation in a switch. That was the method used in the older Deluxe heaters which reversed for heat or defrost. The other motors -- antenna, window, TL compensator etc -- have two separate opposite wound field windings. The windings were connected together at one end which was also connected to the armature and ground was applied to the other side of the armature. In operation one winding was powered and for the opposite direction, the other oppositely wound winding got the power. Being wound differently caused the field N-S relationship to change but because the armature always had power to the same place its NS field stayed the same.
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