However, when I picked the car up I noticed that the fuel and temp gauges stayed at rock bottom, but I know they worked when I dropped it off. I am thinking it is probably coincidence as I can't figure out how the A/C recharge process would impact both of them. I know my temp gauge sending wire is on it's last leg under the hood - the insulation has gotten old and brittle, but it is still connected.
After a bit of research I figured maybe I should check the voltage regulator, which I understood to be behind the clock. When I pulled the clock, I instead found (pictured below) a small shrink-wrapped black plastic square with two wires - which are plugged into two black/green wires from the factory loom. I am guessing it is maybe a tiny solid state version of a regulator? With the ignition on, one wire has 12v and the other has .001v. Maybe it has gone south? I didn't install it, so have no idea.
I was going to test power at the gauges themselves, but looks like I have to pull things apart to get to it so thought I'd ask for input here first.
(I'm so tired of these stupid senders...)