Yes, the van door motor does have thermal overload protection:
http://www.chiefdelphi.com/forums/showthread.php?t=2371 and
http://www.chiefdelphi.com/forums/sh...ad.php?t=11135
What is your gear ratio/winch diameter on the van door motor? We are able to lift at a reasonable speed without coming close to stalling the van door motor.