Compatability

[Chad9883]

 hi all,  I bought the nest learning thermostat on a whim. The compatability checker online isn't making since to me. Here is my current thermostat wiring. Will the learning thermostat work or should I be returning it? 

[CoolingWizard · Accepted solution]

Your system is a basic Heating and Cooling system. Your wires are as follows:

R - Red Wire, goes to Nest Rc

W - White Wire, goes to Nest W1.

Y - Yellow Wire, goes to Nest Y1.

G - Green Wire, goes to Nest G.

It looks like you have a blue wire not used.  This should be used for the Common. You need to make sure that the blue wire is indeed connected to the power common in the furnace.  

AC Cooling Wizard

[Chad9883]

• Thank you. Here is a picture of the terminal at the furnace. It looks like there is a red wire on the C terminal. Would I leave that there and add the blue wire? Also when I put my electrical tester on the C terminal, it's showing not hot. Is that right? 

[Chad9883]

 

[CoolingWizard]

@Chad9883 , that is a basic terminal strip.  It will is rather dirty with dust and lint so I cannot see a wire on the C terminal. Notice the yellow wire in the blue wire nut is the compressor relay control. There is no terminal labeled Y.  If you follow the wire attached to Yellow, you should find another wire with it, the second wire  will be attached to Common. 

AC Cooling Wizard