That is a good video on how determine if you have a battery drain, by measuring the current. Most Digital Multimeters (like the one he used in the video) have a 10 or 20 amp range that can measure the current without using an external resistor.
The problem with using the AMP scale on your DMM is that you run the risk of blowing the fuse in the meter (mine is blown), or worse, on the 10 amp range (unfused) you can blow the whole meter. The 1 ohm resister makes measuring the current draw foolproof. I think I will make one of those test jigs with the resistor for my toolbox.
Anyway, I have determined that I do have a 3+ Amp drain by using DC AMP scale on my multimeter. It was dark and cold last night, so I put off to the next step for today, pulling fuses.
I strongly suspect the AC clutch is the problem. With daylight, I can confirm this by pulling fuses.
What I was hoping for is an answer to why the AC clutch would be getting power, with the ignition switch in the off position.