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Nest Thermostat

Community Member

I switched from heating to air conditioning today. My nest thermostat worked fine for heating. I got short cycles,  power errors, and wifi connection issues on the display. I have no c wire. In order to make the heat work I had to say there was nothing hooked to the c connection, but I had a jumper from my red wire to the c. I have no c wire available. No combination of wiring made any difference in trying to get the air going. Why would the heat work but not the ac? I hooked up the old thermostat and the air is working fine. Any suggestions? 


Community Specialist
Community Specialist

Hello GKohler,


Thank you for taking the time to let us know about your inquiry. I'd be happy to take a look at this for you.


Incorrect wiring configuration or setup could cause odd HVAC activation behavior. To be sure, could you please share with us a photo of your old and new thermostats' wiring setup? Also, the Nest Thermostat connectors are built so that only one wire can be inserted into each connector, so you don't need to use jumper wires. Putting more wire into the terminal can damage your system and your thermostat.


I'll look forward to your response.



I have contacted the Google support. And they have directed me to ship it back for replacement.  They checked it out  remotely and made that decision. Can you be contacted for future needs, if it becomes necessary when I get the replacement?

Community Specialist
Community Specialist

Hi GKohler,


Sounds great! I'm glad to hear we have found a solution by replacing your thermostat. You can give us a shout if you need more help by creating a new thread, and we would be happy to assist you. Also, I'll be locking this thread within 24 hours, unless I can help you with anything else.