A burst of activity happened, and we poked at the central heat/air. Got as far as opening the front panels and turning the thing on. The blower blew air. Huh. We left it on a bit and monitored the air coming from the vents. Not cool, just air. Sorta warm air. Went outside and it was immediately obvious the problem was the exterior unit, which was sitting there quietly doing nothing at all.
Looks like maybe a bad capacitor or possibly a busted condenser. It’s 108 actual degrees outside (no idea the feels like temp), so no one in their right mind is fussing with it today. Or for the immediate future. We'll struggle through the rest of summer with the window unit, and when cooler weather finally arrives, we'll get to work before winter sets in. While we have an alternative cooling source, without the hvac, we have no heat at all. We got through two winters with only a couple space heaters. Not doing it again. Pure misery.