Today I finally got around to changing out the air box thermostat, per the faq instructions. I bought the new part like a month ago and just now got to doing it. I thought it would be one of those things that didn't need doing, but I would do anyway. It turned out to be a good thing I changed it. The old one was failed, locked in the "hot air" position, with the needle-thing pushed in. That is a poor design, in my opinion.

Anyway, here's what it looked like after successfully changing it (this is the new one, at room temperature):



Here it is (the new one) after putting it in the freezer for a couple hours to test it out (good thing I"m an engineer and thought of that :))



The damper door moved without any trouble, with these artificial temperature changes. The worst part was taking apart the air box to change it out.

The next thing is that this means it's been drawing in pure hot air for however long that thing has been broken. Do you think I need a new AMM? It's a Bosch, 1991 non turbo.