New Nest Thermostat - Not cooling

[CAFerris]

I’ve followed the instructions completely, and ensured that the wires are stripped back and inserted into the star connector properly. But there is no cold air during Cool Mode, it just runs the fan. The pre-existing Green wire (which should be Fan) has a small piece of tape on it… as if to indicate that it’s been used for some other purpose. I don’t have a heat pump or anything fancy… it’s just a standard, 20-year old forced air furnace (that functions perfectly with the old thermostat). Does anyone know what the issue could be? Neither Gemini nor this forum were able to provide an answer (there was a similar post but no answer). Thanks! 

[CAFerris]

[CAFerris]

The old one

[CAFerris]

this is the wiring diagram for the old unit…. 

[CAFerris · Accepted solution]

OK< so I don’t know how you close a topic? But since no one answered me, I just kept trying different things. And I don’t really know what the answer is, to be honest. But the best advice I can give anyone with a similar issue is… make sure, double sure, triple sure, that you have stripped back the wires enough that they poke through the other side or the star connector. I kept focusing on the Y wire since that was supposed to control the compressor… but in actuality, I think the R wire might not have been fully connected. I also might not have given the condenser unit long enough to actually cool the air. This last time, I turned the temp to 65 and went away for 30 min… and when I came back, it was like a walk-in freezer.  

[Patrick_Caezza]

@CAFerris 

If the wires poke through like yours, that is wrong and can damage the baseplate.

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