"... it TRIES to unlock..." is the 'key' here...
Since we know a sliding door will not open until it is unlocked, I would investigate the locking mechanism.
See "Related Questions" below for some specifics - note the one about the door ajar problem has lots of information about the door lock actuators too.
On the left side of the DRIVER
On a Ford Windstar : firewall 1----2----3 4----5----6 front of vehicle > driver
On a Ford Windstar , V6 engine : firewall 1-----2-----3 4-----5-----6 front of vehicle > driver
There are a few reasons why a car would be sliding in snow. It is very likely that the driver is just driving too fast.
Not likely to fit - Ford stretched the driver's door in 1998 in a partial response to Chrysler's introduction of the driver side rear door. (prior to the Windstar getting one in 1999). Check with a local auto salvage yard, or maybe even a body shop - 2 good sources of information on parts interchangeability.
On a 1998 Ford Windstar ( 3.0 and 3.8 ) firewall 1-----2-----3 4-----5-----6 front of vehicle > driver
On a 2001 Ford Windstar : firewall 1-----2-----3 4-----5-----6 front of vehicle > driver
firewall 1-----2-----3 4-----5-----6 front of Ford Windstar>driver ( if that's what you are asking ) Helpfull
On a 2002 Ford Windstar : firewall 1-----2-----3 4-----5-----6 front of vehicle > driver
The fuel pump reset button on a 2003 Ford Windstar is on the driver's left foot area. It is next to the hood release.
On a Ford Windstar , V6 engine : firewall 1-----2-----3 4-----5-----6 front of vehicle > driver
Remove it by depressing the retainer tab then sliding the knob out of its latch case. Alternatively, you can use a flat screw driver to insert it behind the knob to force it out.