Biohazard

I got the heater box out without removing the dash frame. This reinforced the notion that...I really want to remove the dash frame, lol. The cleaning process will be easier and more effective and the reassembly will be immensely more pleasant.

Draining the coolant. Hah! I thought the antifreeze was in good shape because it seemed like one of those simple things that the grandson might have done when he put in the new plugs, wires, and filter and the color of the coolant looked really fresh when viewed at the radiator cap. Well, dumping the coolant into a bucket was very revealing as a pantload of sediment drained out with it and quickly settled to the bottom. Boy am I glad I did that! I'll be doing a very thorough flushing of the whole system and refilling with fresh stuff.

The heater box itself had some stuck-on insulation which I soaked with Windex (I had an econo jug of it and it's ammonia-based) to loosen. Sprayed the heater core and A/C evaporator with it, too, and then hosed everything off. Ran inside to check on the availability of replacement seals, gaskets and such but it hardly matters since it all has to go anyway. It's just nice to know that all that stuff is readily replaceable. Sprayed everything with the Windex, let it sit, then rinsed. Ultimately, it will all get re-treated with pure ammonia.

The heater core belched rusty water and more sediment when fresh water was pushed through it at the inlet and outlet. Ran it through in both directions till clean water consistently poured back out.

Just needed to give this whole assembly a cursory cleaning off to reduce its hazardousness while sitting in the driveway.