topic AC not cooling sometimes usually in late afternoon in Nest Thermostats

AC not cooling sometimes usually in late afternoon

scampbyc — Tue, 09 Aug 2022 21:32:38 GMT

There is an intermittent cooling problem. This usually happens in the afternoon or at night, or hot days when the AC need to work for a while. It stops blowing cold air but instead blows warm air inside when the temperature reaches the set temperature. The AC keeps running but not cooling since it blows out warm air. The temperature rises up. I reset the thermostat and I turned off the Airwave function but it does not solve this problem. Any thoughts? Thank you.

Re: AC not cooling sometimes usually in late afternoon

Masyukun — Tue, 09 Aug 2022 22:07:29 GMT

I've had similar issues with my Nest, and realized it's because I consented to allow my electric utility company SMUD to communicate with the Nest to tweak settings based on demand. Basically, 5pm - 8pm are the highest of the high peaks for the rate-based tiered pricing (and also demand) so the A/C basically stops during those 3 hours. It kicks back in automagically at 8pm -- sweet relief.

Re: AC not cooling sometimes usually in late afternoon

scampbyc — Tue, 09 Aug 2022 22:12:24 GMT

Thank you. In my case, the outside unit fan is still running, but just not cooling.

Re: AC not cooling sometimes usually in late afternoon

Masyukun — Tue, 09 Aug 2022 23:22:22 GMT

I suppose it's possible it changed to a "fan only" setting, but that should be visible in the thermostat setting. Also, even though Nest tries to push my temperature up during this time, I can manually swing it down for a few minutes and it will start to cool again.

I wonder if this might not be an issue with the AC itself.

Re: AC not cooling sometimes usually in late afternoon

Anonymous — Wed, 10 Aug 2022 02:52:03 GMT

With the heat, make sure your AC unit is working correctly. There are some videos on YouTube you can check out if you feel comfortable. Search AC capacitor or troubleshooting. I’d say go outside, have someone turn on the AC in the house and listen for your AC compressor to kick on. There is also a contactor switch (under the cover) you can visually watch it engage when someone turns the AC on in the house. If you feel comfortable, you might also reset the AC switch at the breaker. Dollars to donuts if your unit is 5+ years old, I’d be leaning toward the capacitor failing. What you’re describing I’ve been through that same thing and it was a $35 part (capacitor) on Amazon… or a $400 call to an HVAC company. Good luck!

Re: AC not cooling sometimes usually in late afternoon

scampbyc — Wed, 10 Aug 2022 03:05:24 GMT

Thank you! I have several contractors from warranty company serviced but not solve the problem yet. Already spent more than $500. Thank you for your suggestion.

Re: AC not cooling sometimes usually in late afternoon

Anonymous — Wed, 10 Aug 2022 03:14:53 GMT

You’re welcome. Mine went in phases over 4 days. So first was intermittent cooling, almost worthless during the day, didn’t work well at night. Turning it off for a while almost seemed to help it cool again. Next, the fan stopped spinning so I used the ‘push test’ (leather gloves and a pry bar) and reached in and tapped the fan blade so the fan would spin on its own. Cooling was almost back to normal for one evening only. Next, I could no longer ‘tap start / push start’ the fan and it was completely out and soon after the compressor was no longer starting.

Replacing the capacitor is what made it work again and the cooling was right back to normal again and even cooler than before as the failing capacitor wasn’t allowing the compressor to do its job (and you don’t want the compressor to fail from a bad capacitor). I attached the picture of the part on my unit. It took a darn week to arrive and I had to go out of town so I couldn’t leave my wife and pets without AC so I ended up paying the $380 for the HVAC company to repair it. They did the inspection, said it was the capacitor like I suspected, and replaced it and tested the system. The problem is, no one seems to carry this part locally and it’s funny that I found out after this issue a number of my friends and family have all replaced the part and gone through the same thing. I attached a picture of the part.

Re: AC not cooling sometimes usually in late afternoon

scampbyc — Wed, 10 Aug 2022 03:19:36 GMT

Thank you so much. really appreciated. It is so detailed. I'll ask the contractor to check the capacitor as I am good at those stuff.

Re: AC not cooling sometimes usually in late afternoon

Anonymous — Wed, 10 Aug 2022 03:22:36 GMT

For what it’s worth, $110 of that $380 I paid was for the HVAC company to send a guy to check the unit and tell me exactly what was wrong with it, the rest was the part, taxes, and the install.

I used this video to point me in the right direction. The guy is a blessing for putting it out there. https://youtu.be/wzAA4dlp_70

Re: AC not cooling sometimes usually in late afternoon

MelbaDT — Wed, 17 Aug 2022 09:05:15 GMT

Hey folks,

Sorry for the delay here but thanks Removing-Nest for your very helpful insights and suggestions — this is greatly appreciated.

scampbyc, how's it going now? Have you had the chance to get in touch with your contractor already?

Best,

Melba

Re: AC not cooling sometimes usually in late afternoon

scampbyc — Wed, 17 Aug 2022 12:01:22 GMT

Thanks for replying. My contractor will come today to change the condenser fan and capacitor. I will keep you updated. Recently it is not hot, so it is hard to get that problem.

Re: AC not cooling sometimes usually in late afternoon

MelbaDT — Thu, 18 Aug 2022 04:58:46 GMT

Hey scampbyc,

Understood — we'll be waiting for your update.

Best,

Melba

Re: AC not cooling sometimes usually in late afternoon

Ryan_G — Sun, 21 Aug 2022 11:29:08 GMT

Hey everyone,

I'd like to jump in here and check if you've seen Melba's response. Let us know if you need more help by replying to this thread.

Thank you for your help, Melba.

Regards,
Ryan

Re: AC not cooling sometimes usually in late afternoon

scampbyc — Sun, 21 Aug 2022 17:59:43 GMT

After changing the condenser fan and capacitor, the problem was not solved. Frustrated.

Re: AC not cooling sometimes usually in late afternoon

Ryan_G — Wed, 24 Aug 2022 17:46:10 GMT

Hi scampbyc,

Thanks for the reply and we're sorry for the delay.

Were you able to try doing a complete reset on your Nest Thermostat? Also, have you tried connecting the old thermostat and checked if it is going to be the same behavior?

Regards,

Ryan

Re: AC not cooling sometimes usually in late afternoon

MelbaDT — Sun, 28 Aug 2022 09:04:02 GMT

Hey there,

Checking back in ― how's it going with your thermostat? Have you had the chance to try the suggested steps above?

Best,

Melba

Re: AC not cooling sometimes usually in late afternoon

MelbaDT — Mon, 29 Aug 2022 15:17:44 GMT

Hi,

We haven't heard from you in a while so we'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the Community.

Best,

Melba

Re: AC not cooling sometimes usually in late afternoon

scampbyc — Tue, 30 Aug 2022 01:41:04 GMT

Hi All, it seems the problem is from the Nest learning thermostat. After I changed to a new Nest thermostat, I haven't see the problem so far.

Re: AC not cooling sometimes usually in late afternoon

MelbaDT — Wed, 31 Aug 2022 17:24:46 GMT

Hey scampbyc,

Thanks for getting back to us and for sharing what you've done to have your concern resolved. We're also glad that you now have a working thermostat with your HVAC system.

Feel free to let us know if you have any further questions in mind.

Best,

Melba

Re: AC not cooling sometimes usually in late afternoon

MelbaDT — Sun, 04 Sep 2022 11:31:20 GMT

Hi,

Best,

Melba