Disclaimer: This thread was migrated from our previous version of the Google Nest Community. You can continue to receive updates on your thread issue here or simply ask, browse or more in the new Google Nest Community.
Original Poster: Chris 3295
I have one air conditioning unit and one furnace that serves both the upstairs and downstairs to a 1,700 townhouse (no heat pump). I replaced our old thermostat on the first floor with a Nest about a month ago and it has worked great from day one - A/C has been working perfectly. Since I knew it was working fine downstairs for several weeks I decided to purchase a second Nest to replace the old thermostat upstairs, even though the old thermostat was working fine and A/C upstairs works great. As you can see by the pictures, the wiring is identical for both of the old thermostats, and I used the exact same wiring for both of the new Nests. However, although the downstairs Nest works fine, the Nest upstairs appears to be kicking the A/C on, but barely. While installing the Next upstairs the temp got to about 82, so after installation I set the A/C temp on the Nest upstairs to 75 but it won't get the temp below 78/79. I let it run for 4-5 hours but it just wouldn't go below 78/79 and gets very humid upstairs. I re-installed the old thermostat upstairs and the A/C then works fine again and went down to 75 within 20-30 minutes. I completely wiped/deleted the Nest upstairs from the Google Home iOS app and started from scratch, re-installed the new Nest, but got the exact same results. It seems to try to work, but just does not cool the upstairs down. I went through the whole app installation process and the app did not detect any wiring issues at all. Any ideas or changes that I can try?
