I’ve successfully removed the windshield cowl and cleaned out the leaves, fir needles, and mouse nest by the cabin air intake, which will hopefully solve that part of the problem. (I’m a bit embarrassed I didn’t do this first, since it was full of debris, some of which is now in the blower fan, so I’ll be cleaning that out again…) Thank you to arlindsay1992 for the advice on this!
In regards to the second issue, I’ve partially taken apart the dash, but am having trouble with the passenger’s side register. Following the instructions on page BO-45 of the repair manual, it looks like there are four clips that I’ll need to push down to remove it. I’ve gotten it partially out on top, but am not having any success with finding the bottom set of clips. I did see a YouTube video which indicates that, once the top is partially out, the vent part needs to be removed from the “frame” of the register, and the clips pushed down from inside to get the frame out. But I’m not sure how to get this vent part out.
I’ve also pulled off the cover for the controls for the fan system (sorry if it has a more precise name that I don’t yet know!) and can see the levers and the blue HVAC cable. This may be just showing my ignorance, but how would I know if the blue HVAC cable is bent and should be replaced? Also, the metal lever for adjusting the temperature feels wobbly top-to-bottom, and is stiff trying to move it left-to-right. Could the problem just be that it is bent or loose somewhere? Thanks!