Google Nest (Gen4 - 2024) Installing to 4-Wire System

[Denny_Crane]

Someone else here had this same issue, previously (about a year ago, IIRC), but unfortunately the solution did not work for me.

The thermostat and app only read heat - no a/c. Heat works, but obviously we need a/c too.

I have 4 wires, previously connected to our Honeywell; blue, white, green and red. Everything seemed intuitive and simple, until the blue. Some directions say connect to the C input - didn't work. Switched to Y - didn't work. Do I need some sort of bridge?

Frankly, it'll be cheaper and easier to just put something else back in its place - possibly even a Nest Gen 3 or earlier - than hire an electrician, if I can do this myself.

Any assistance is appreciated. 🍻

[CoolingWizard]

@Denny_Crane ,

Please post the picture of the Honeywell thermostat with the sires attached before you removed it. We need more information about your system in order to help you best.

Make and Model number of Indoor Air handler:

Make and Model number of outdoor Condenser Unit

 Model number for original Honeywell Thermostat.

AC Cooling Wiarard

[Denny_Crane]

Thank you, but you have all the information you need, above.

This is not an HVAC issue. It's a wiring one - a simple one at that. One of literally three things is to be done here:
1. The blue wire is in the wrong slot/receptacle. 
2. It needs a bridge wire. Or...
3. It necessitates a fifth wire be tapped (by far, the least likely, as the digital Honeywell before it worked swimmingly with the 4 wires provided).

That's it. Any further information not only is unnecessary, but risks complicating and confusing this issue far beyond its parameters. 

I appreciate your input, but this is fast, easy fix for any professional with half a notch more than my level of knowledge. 🍻

[CoolingWizard]

@Denny_Crane ,

I disagree with you.  You say I have all the information I need.  there’s not a thermostat ever invented that knows how to read the color of the wire. I know that you have a blue wire and you tried putting the blue wire on C and it didn’t work and you tried putting the blue wire on Y it did not work.   
I know you have Blue, a White, a Green, and a Red wire.  On the old Honeywell thermostat what letter terminal was each wire connected to?

AC Cooling Wizard

[Denny_Crane]

HVAC guy just left. The wiring and installation were perfect.

It was literally a factory reset of the nest system/unit, which I neglected to do, after placing the blue wire in Y. 

I had a feeling.