how to repair sliding door failure to close?

maybe the striker bolt is misaligned

The sliding door will not close in cold weather when the rear locking mechanism freezes or binds. If you warm up the car in a warm garage (or run with heat on high for an hour or more), the locking mechanism will work again. A temporary fix is to spray grease into the rear locking mechanism (in door, not the latch on the van body)and saturate it so that the latch mechanism stays slippery. Repeat weekly in cold weather for optimal results.