Not cooling

[DAR]

My thermostat says that it is cooling but it won't turn on the AC until I lower the thermostat setting about 3-4 degrees.  What could be causing this?

[Jenelyn_O]

Hi DAR,
 

Thanks for reaching out. A few questions: what type of Nest thermostat do you have? You can visit this link to check what type of thermostat you have. Do you see any messages or code on your thermostat screen? What type of air comes out of your vent?
 

Best,

Jenelyn

[DAR]

It's a nest learning thermostat 3rd generation.  There are no error codes. The screen turns blue but it takes a long time to start up but I'm not sure if that is normal.

[Markjosephp]

Hello there,

I wanted to stop by and see how I could help.

Thanks for the help here, Jenelyn.

@DAR, thanks for letting us know. A power related issue could be the cause of your AC not working. I'd love to know more about this. Could you please share with us a photo of your thermostat's wiring? Are you getting any delay timer showing on the screen? Also, check its power readings in the Technical Info settings.

I'll look forward to your response.

Regards,

Mark

[DAR]

The ac is working fine when it starts up it's just that i have to lower the thermostat setting about 3 or 4 degrees lower than the room temperature is to get it to start up.

[Markjosephp]

Hi Dar,

Gotcha! Does your thermostat have a C-wire connected? If so, could you help me check its power readings on your thermostat's Technical Info? This will help us determine what could be the reason.

Thanks,

Mark

[DAR]

Yes there is a C wire connected.

[Markjosephp]

Hi there,

Thanks for the screenshot, DAR. It appears that the battery level is in good condition. Could you also check the VOC, Vin, and LIN? You can find these on your actual thermostat's technical information.

Regards,

Mark

[DAR]

I don't know where to find that but everything is wired correctly.  If the indoor temperature is 78 I can't get the cooling to start up until I set the cooling to around 73 or 74.

 

[Markjosephp]

Hello there,

I appreciate your efforts, DAR. No worries! I got the details that I needed. Your Nest Thermostat and your HVAC system are working as intended. I understand why it won't turn on right away, even if it's only a degree above the current temperature.The algorithm should be at least a 2–3 degree difference from the current temperature in order to give the system ample time to generate cooling or heating.

The best example of this is when your thermostat reaches your desired temperature; it'll stop your system and turn on automatically when it detects the 2-3 degree temperature difference.

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

Regards,

Mark

[DAR]

Well I guess it's working properly then correct?  I'm guessing that it does that to prevent the compressor from overheating and burning out.

[Markjosephp]

Hi DAR,

You got it! It'll help your system by giving it more time to cool down and prevent sudden activation, which might damage your system. 

Best,

Mark

[DAR]

Thanks 👍

[Markjosephp]

Hello DAR,

I'm glad to help! If there’s anything else I can help you with, please let me know.

Regards,

Mark

[DAR]

I still think it should come on.  It says 30 minutes but it's been over 2 hours now and it won't start up unless I lower it to 73 degrees.  The cooling doesn't start up until the inside temperature is 82.  The heating starts up when the inside temperature is 71.

 

[Markjosephp]

Hi there,

Oh! Thanks for bringing this up, DAR. Let's sort this out.

Please go to your actual Nest Thermostat device installed in the wall and navigate it to Settings > Technical Info > Power. From here, you should see the Voc, Vin, and lin. This will help me determine the power state your thermostat is in.

Also, could you give this step a try? Run a system test by going to Equipment Settings > Continue > Test. Activate both heating and cooling to see if they start running right away.

Keep me posted.

Best,

Mark

[DAR]

38.01 volts and the battery is 3.96 volts and yes the heat and the cool does start running right away.  The problem is that since I have to set the cooling 4-5 degrees cooler than the room temperature is the house gets too cold.  The sensitivity needs to be increased so the cooling will cycle on and off more often if you know what I mean.  PS: for some reason it seems to be cycling properly now but it is an intermittent issue.

[Markjosephp]

Hello DAR,

Gotcha! If you recently installed and paired your Nest Thermostat, I would suggest disabling the auto-learning feature in order for your thermostat to only follow your set temperatures, as it seems that power issues are no longer related to what you're experiencing. In the meantime, please keep observing its behavior and keep me posted if anything comes up.

Thanks,

Mark

[DAR]

How do I disable the auto learning feature?

[Markjosephp]

Hi there,

On the Nest app's homepage. Select your thermostat and tap Settings in the upper-right corner. Scroll down until you see Auto-schedule. Disable it if it's turned on. Also, restart your thermostat to make sure it will reflect the changes.

Thanks,

Mark

[DAR]

Okay thanks it was already disabled 👍

[Markjosephp]

Hey there,

Thanks for the effort, DAR. Please keep an eye out on your thermostat, at least within the next 24 hours, and keep me in the loop on how things progress.

Best,

Mark

[DAR]

I think it's probably normal for the delay in order to protect the compressor but I'm not quite sure about that.

[Markjosephp · Accepted solution]

Hi there,

That's right, DAR. Just like what we have discussed, it still depends on the current temperature and your target temperature to determine how long it will take to reach the set temperature, so your AC unit takes time to generate cool air. If there’s anything else I can help you with, please let me know.

Thanks,

Mark

[Dan_A]

Hello there DAR,

I wanted to follow up and see if you still need help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Regards,

Dan

[Dan_A]

Hi DAR,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread. 
 

Cheers,

Dan