Nest thermostat reading a fault “problem with a wire” diagnose and repair.

This thing said it had a problem with the W1, with the W1 wire. So we're going to do a few tests here. 21 volts. That's a good bit, so I'm going to put my amp meter on that. I'm looking for a fuse. It's going 5 amps, so more to Gagin. I'm going to cruise across this real quick. Going forward, I don't know if that will record it. Jumping from red to white again. 5 amps. That'll be quick. Back up here, contactor. See if that doesn't clear up the problem. To even get back into the thermostat, The heat pump came on and started running. So that Nest thermostat kept a low voltage short from burning up the contactor. I didn't know they would do that.