Great, thank you for the detailed explanation! I’ll remove the windshield cowl as soon as I get a Phillips screwdriver with a short enough handle so it’ll fit under the hood and I can take those three screws out.
I don’t know if it has a plastic screen, but I’ll check. And there’s no A/C.
Also, thank you for the advice about the heater valve and HVAC, and that I should not force the levers to move! I’ll try to take things apart and clean them, and see how far I get; if it turns out to be beyond my skill level I’ll bring it to a professional mechanic. Do you have any recommendations for minimizing the risk of breaking parts when taking apart the dash? I admittedly don’t have a lot of practice with things like this but I hope to learn.
Thanks!