I bought a nest thermostat to replace my old thermostat. I Removed the old thermostat and installed the new one like the instructions said. Once hooked up it says the blue and yellow wires are not detected. I striped the wires back and tried again. Same problem. I removed the nest thermostat and reinstalled my old thermostat and it works perfectly. It's just old and needs to be replaced. Thanks for any suggestions to this problem. I'm thinking the nest is defective!
No pictures were taken. I did attach yellow, blue, white top to bottom on left side, and green then red on the right. Tabs remained down when wire was pushed in about a ¼ inch.
My old thermostat does have a jumper connecting R and Rc.
@jswoodworks , the proper insertion distance for the nest thermostat back plate is approximately 3/8”. When you insert the wire you’ll notice it a little stop and then you push harder and it goes right past that to the next stop and that’s where it needs to be at.
AC Cooling Wizard
NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
