Buick Terraza was created in 2005.

Usually under the hood on passenger side under screen by wiper blade

I found my cabin air filters (2), inside the glove box, on the wall, under a lid. If your air filters are very dirty, I would recommend removing all your glove box contents. Also, after replacing the filters, I had a great increase in air movement from the dash vents. I paid about $25 to $30 for the 2 filters. This is very easy to do and requires No Tools.

This is most likely due to a blown fuse. Even if the brakes are good, a blown fuse will cause this symptom. If, after replacing the fuse, it blows again within a few weeks, additional maintenance may be required.

If your problem is that the door keeps opening and doesn't want to latch shut, then what I have been doing is carrying a piece of 3M scrubbing pad and use that to scuff up the contacts on the door and the door jam contacts. Then the door functions properly for another month or so.

There is a recall on the automatic sliding doors and it involves them not latching.