The motor it self should work even in cold weather just as power window motor, I guess.

The fact that it does not operate in cold might be an indication that there is water leakage: water goes in and then freezes.

It water leaks, it will make problems in the future: more rust inside, permanent damage of sunroof motor, . . . $$$



Last summer, I found a paint blister area right behind the black rubber (on the roof, not the moving panel).

The correct thing is to remove the rubber and treat the rust, but I did not remove the rubber.
I just applied POR-15. I pulled the rubber a little so that PO5-15 can reach deeper.