I just had AC installed and found at that there's a short in the base. Whenever we plug in the wire for the AC to the base, it turns on the AC unit and starts running it. This is before plugging the display back in over the base. We checked the resistance between the Y1 and the Rc and it was indeed a short. It would be if you ran a wire directly from Rc to Y1. By we I mean me and the AC installer. They install these all the time. Anyway, I'd had the thing for a few years so it wasn't under warranty anymore. The base can be purchased here:
https://store.google.com/us/product/nest_learning_thermostat_3rd_gen_base?hl=en-US
But if you click the link you can see it's out of stock. My question is when did it go out of stock. And when will it be back in stock. They still sell the whole thermostat online, so it's not like they've discontinued the part. I saw some of these available on ebay, but they're marked up considerably from the $50 google has it listed for and they're even labeled as refurbished. Not exactly confidence inspiring. It's still mid March and I won't need the AC in my area for a few months at least, so I figured I can wait to see if this will come back in stock before resorting to other measures. I even took the back of the base off hoping I could figure out where the short is, but it's a full on circuit board and with out the diagram and an electrical engineering degree and very specialized tools there's no way to fix it, if that's even possible.
