I have 12 VDC motors which are car seat motors around 50W. Can I use them on AC? I believe they are PM motors.

 

Brushed-Permanent-Magnet-Motors will not run on AC-Voltage.
When the polarity of the Voltage reverses, the motor will run in reverse.

Where do You expect to obtain ~12-Volts-AC at more than ~10-Amps ?
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If you have 12vac, all you need is a bridge rectifier, that is, if the 12v supply has the current capability.

 

Giving up on the spring loaded spool idea after receiving valid comments. Now thinking of using my 120VAC Snowthrower after converting it for 60VDC, then won't need a power cord. Guess will have to rewind the motor for 60VDC. Any thoughts/ideas?

 

You do not seem to have a very solid understanding of how things work. There really is no substitute for the right components.

 

Its a PM field motor so rewiring the armature is just not a practical solution.