https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-failed-install/m-p/87941#M19700 <P>I would suspect incorrect wiring, since you changed out the thermostat wiring.&nbsp; Pretty easy to do, especially when looking inside at the furnace control board.&nbsp; &nbsp;I suggest that you start at your furnace control board and make a list of the wire colors on each terminal.&nbsp; And then go back to your Nest base and make sure the same colors are going to the same terminals on the Nest.&nbsp; And make sure none of the wires have too much bare wire showing and not touching any other wires.&nbsp; A typical system will have:<BR />R - red wire - 24v power<BR />W - white wire - heat control<BR />Y1 - yellow wire - cooling control<BR />G - green wire - fan control<BR />C - blue wire - 24v common - (I have sometimes seen brown or black instead)</P><P>If this is a typical gas furnace with an outside compressor for A/C, you will also have a 2-wire bundle coming to the furnace control board from the outside compressor.&nbsp; One wire will connect to Y1, and the other wire goes to C.&nbsp; So on the furnace control board, you will probably see 2 connections to Y1 and 2 connections to C.</P> Thu, 20 Jan 2022 00:08:02 GMT johnCNA 2022-01-20T00:08:02Z https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-failed-install/m-p/87731#M19673 <P>Hi guys. &nbsp;Installed the nest after running new 5 wire to new unit. Exchanged the old 4 wire with the new 5 wire which gave me C wire for power. &nbsp;When I turn on heat, it just blows air. The heat doesn’t come on. When I turn off the unit. The heat then turns on. &nbsp;Without the nest on. &nbsp;When I want to turn off the heat. I have to reset the nest and then the heat turns off. &nbsp; My wire config is &nbsp;W-R-G-B-Y1. Any help would rock. As it’s gonna get cold agin this weekend&nbsp;</P> Wed, 19 Jan 2022 21:11:56 GMT https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-failed-install/m-p/87731#M19673 Propfuy 2022-01-19T21:11:56Z https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-failed-install/m-p/87941#M19700 <P>I would suspect incorrect wiring, since you changed out the thermostat wiring.&nbsp; Pretty easy to do, especially when looking inside at the furnace control board.&nbsp; &nbsp;I suggest that you start at your furnace control board and make a list of the wire colors on each terminal.&nbsp; And then go back to your Nest base and make sure the same colors are going to the same terminals on the Nest.&nbsp; And make sure none of the wires have too much bare wire showing and not touching any other wires.&nbsp; A typical system will have:<BR />R - red wire - 24v power<BR />W - white wire - heat control<BR />Y1 - yellow wire - cooling control<BR />G - green wire - fan control<BR />C - blue wire - 24v common - (I have sometimes seen brown or black instead)</P><P>If this is a typical gas furnace with an outside compressor for A/C, you will also have a 2-wire bundle coming to the furnace control board from the outside compressor.&nbsp; One wire will connect to Y1, and the other wire goes to C.&nbsp; So on the furnace control board, you will probably see 2 connections to Y1 and 2 connections to C.</P> Thu, 20 Jan 2022 00:08:02 GMT https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-failed-install/m-p/87941#M19700 johnCNA 2022-01-20T00:08:02Z