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Nest failed install

Propfuy
Community Member

Hi guys.  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.  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.  Without the nest on.  When I want to turn off the heat. I have to reset the nest and then the heat turns off.   My wire config is  W-R-G-B-Y1. Any help would rock. As it’s gonna get cold agin this weekend 

1 REPLY 1

johnCNA
Bronze
Bronze

I would suspect incorrect wiring, since you changed out the thermostat wiring.  Pretty easy to do, especially when looking inside at the furnace control board.   I suggest that you start at your furnace control board and make a list of the wire colors on each terminal.  And then go back to your Nest base and make sure the same colors are going to the same terminals on the Nest.  And make sure none of the wires have too much bare wire showing and not touching any other wires.  A typical system will have:
R - red wire - 24v power
W - white wire - heat control
Y1 - yellow wire - cooling control
G - green wire - fan control
C - blue wire - 24v common - (I have sometimes seen brown or black instead)

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.  One wire will connect to Y1, and the other wire goes to C.  So on the furnace control board, you will probably see 2 connections to Y1 and 2 connections to C.