topic Re: A/C not working on new install in Nest Thermostats

A/C not working on new install

Pdq1966 — Fri, 24 Jun 2022 03:37:31 GMT

Brand new install, zoned system, downstairs have a 5 wire nest learning thermostat and upstairs I have the less expensive nest thermostat. I am having issues with the one upstairs.

I have tried two separate nest thermostats and they both will work for cooling. This is a five wire, fan, heat, cool, common, power system. Everything works fine with a honeywell unit that was new and tested by my hvac sub contractor.

All the wires are landed correctly and the nest says cooling but neither the fan nor the ac will come on. Unhooking the cooling wire and it will run fine with no errors, except it won't run the ac. Unhook the common wire and still nothing.

I have reset and tested multiple times. All with same results. No errors and the unit thinks it's running with nothing happening. Hook ac/fan/power together and ac kicks on. It's in the thermostat somewhere? About ready to send both back.

Frustrated.

Re: A/C not working on new install

DanMag — Fri, 24 Jun 2022 10:17:03 GMT

Try telling thermostat you have 4 wires connected when it ask at set up. Dont tell it you have common hooked up but keep it hooked up

Re: A/C not working on new install

EdwardT — Mon, 27 Jun 2022 17:44:10 GMT

Hi folks,

@DanMag, thanks for the help!

@Pdq1966, hows's it going with your Nest Thermostat? If you're still having the same issue, please let us know the following information:

How is your Nest Thermostat wired?
What is the power readings of your Nest Thermostat? You can find this information by going to Settings > Technical Info > Power.

Looking forward to your response.

Thanks,

Edward

Re: A/C not working on new install

Pdq1966 — Tue, 28 Jun 2022 13:17:48 GMT

It only runs A/C if you I disconnect the heating wire (white wire). I guess I will have to hook up the heat when it gets to be winter. I just don't get it. I assure you it is wired correctly and I checked continuity on all of the wires. It is some internal programming issues. Interestingly enough I can also disconnect the A/C (yellow wire) and it will run the fan (green wire) thinking it is cooling. I really wish I would have just invested in the learning thermostat because these lower models don't have the options and troubleshooting is more difficult. So, no, I haven't solved it yet. Just figured out how to make it work for what I need now.

Paul

Re: A/C not working on new install

EdwardT — Tue, 28 Jun 2022 16:25:17 GMT

Hi Pdq1966,

Thanks for the response. I'm sorry to hear that you're still having the same issue but I'm glad that you figured out a way to get it to work for now. If you have the time to troubleshoot, just respond with the information that I was asking from my previous response so we can investigate further.

Thanks,

Edward

Re: A/C not working on new install

MelbaDT — Sat, 02 Jul 2022 07:53:01 GMT

Hey there,

Just letting you know that we'll be locking this thread after a day if we don't receive an update from you. Once you're ready to proceed with the troubleshooting, feel free to start a new thread in the Community.

Best,

Melba