Today my Jeep didn't start. I last drove it on Saturday. Nothing I could find was "on" that might have drained the battery. Jumped it, it started pretty quickly, and then that was that. I drove it around to run errands and it started up every time I needed it to. 14v when running, 12v when key is on but the engine is off. While I was out, I happened to look down and notice the engine temp WAY above where it should normally be. I drove more, it went down, I stopped at lights and it crept back up. Eventually it got high enough that the "check gauges" light came on, so I just went home on a route that had no traffic to keep things cool. At home with the key in the ignition and in the on position, the electric fan should have been running to cool the engine, but it wasn't. I could spin the fan freely, but it made no attempt to run on its own. I need to get my multimeter out and try to figure it out, so I'm assuming if I disconnect the plug closest to the fan and put the probes in, I should see a high(er) voltage when it's above temp and the fan should be running, and the voltage would go low when the engine gets back down to normal temps. That would tell me it's a bad fan motor. If it's consistently low, even when the temp is up and the fan should be running, then it should be a fuse or relay or whatever. Does that all sound right? Also, what could the flat battery situation have to do with the fan? Not related at all?