Putting my MIL's 240 back together I noticed a couple of curious things. The important one was that the hot/cold flapper in the airbox was non-functional. The thermostat probably works, but the part it pushes against to flip the flap is broken. The AMM was saved probably just by the fact that the pre-heat hose was also busted.

Given that this isn't Cali and we have no inspection, I decided to not bother with the pre-heater and the flapper. I have my doubts about it being very effective for anything anyway.

The solution is simple. The flapper/thermostat assembly pops right out of the airbox, it's a separate piece. The inlet for the pre-heat tube is most perfectly capped off with a 1 1/2" (38mm) rubber plumbing cap available at any home improvement store. I wanted to cap it because it's at the bottom and might suck up road junk or water. If you don't have tentacles for hands you have to pull the airbox to do it comfortably, but that't not very complex.

Now, I don't have to worry about AMM cooking. Those things are spendy.