so I had issues with my passenger door not shutting, and took it to a shop and they determined it was the latching mechanism. (Btw this was in the winter 10-30 degrees) so fast forward I got my hands on a new latch, thanks to fine people on this forum, and it is now warmer, but I was washing my car, got done cleaning the door jams, shut my door annnnnd it shut all the way! So first question, what would be failing in the winter but working in the summer? And second question is, I do have to “slam” it to fully get it to shut, not related to air pressure inside, because it’s the same whether there’s a window or door open. But what do you guys think the failing part could be?

It may not be a part issue but an adjustment issue. IIRC there’s some adjustment on the hoop. Try moving the latch hoop on the car out a millimeter at a time and see if it improves.

Oh I didn’t know there was an adjustment, I’ll mess with that and see what I can find out thanks! And one of the first things I did was put wd40 in it before it was stored for the winter, so maybe that did play a role in it? But thanks for both insights, def helpful!