Why Is Nest Thermostat Not Turning On AC Compressor?

If the Nest thermostat not turning on AC compressor, the issue is most likely occurring due to the thermostat itself.

However, there are more root causes that we should also discuss, preventing your thermostat from turning on the AC.

Issues with the ACs could also occur due to the power supply, hardware functionality, and internal components.

If the Nest thermostat is not turning on the AC’s compressor, there may be loose wires or the batteries of the thermostat had reached the end of their lifespan. A power problem with the AC is also possible or the WiFi router is not close enough to the device.

Let’s look up the root causes of the problem is even greater detail before you attempt to solve the problem.

Why Is Nest Thermostat Not Turning On AC Compressor?

If your Nest thermostat is unable to turn on the AC it tends to be connected with, the fault can either be with the thermostat itself or with the AC.

Either way, there are plenty of things you can attempt to solve the problem, and later we will get you familiar with all of them.

For now, here’s what’s preventing the Nest thermo-unit from starting up the AC’s compressor:

1. Loose Wires

Users admit that in most cases, they observed loose wires in their setup, which is essentially preventing the thermostat from turning on.

2. No Batteries In Thermostat

The batteries inside of the Nest thermostat may need replacement before the device can turn on the AC.

3. No WiFi

Nest thermostat is dependent on its WiFi connection, and you may have to bring the router closer for the device to get sufficient internet.

4. The Issue with the AC

Your AC may have gotten disconnected, or its compressor has run into a fault, which will prevent the device from turning on at all.

5. Hardware Problem

There may be a hardware issue observed somewhere across your setup, which you’re not clearly aware of.

This was everything you should know about the problem with the Nest thermostat.

Check out the fix methods we’ve extracted to solve the problem with the AC compressor.

How To Fix When Nest Thermostat Not Turning On AC Unit?

Now that you know better what is wrong with that thermostat and supposedly why is it not turning on the AC compressor, let’s move on to fixing the issue.

Just keep in mind to follow the order of our solutions for the best effects at the troubleshooting.

Here’s how to solve the Nest thermostat and AC compressor problem you’re having:

Solution #1 Insert Nest Wires Correctly

Chances are that your Nest thermostat isn’t starting up the AC due to incorrectly connected wires.

This can often happen if you disengage and mess with the wire setup and essentially break the connection of your thermostat with the entire HVAC system.

Generally, the crucial wire that your thermostat requires to turn on the AC is the RC wire (Red Cooling wire), which should be attached to the correct terminal.

Here’s how to reinstall the RC wire correctly in your Nest thermostat:

1. Take the Nest thermostat off the wall.
2. Open the wires compartment and locate the RC wire and the RC terminal.
3. Detach the RC wire from its current slot and attach it to the terminal, which has “RC” labeled on itself.
4. Ensure that the wire is attached properly and reinstall the thermostat.
5. Test.

Note: In regard to the other wires, ensure that they are securely connected and attached to their terminals.

Solution #2 Move Router Closer To Nest

As with the other thermostats, Nest also requires an active internet connection to support your ACs and turn them respectively ON and OFF.

Chances are that your router is not close enough to the thermostat, which will result in this very same problem you’re experiencing.

In that solution, you should position the router closer to the thermostat so the internet doesn’t get suspended over the range it has to travel.

Ensure that the router is positioned in close proximity (5-10 meters)from the thermostat.

Note: You can also go over 20 meters, but that’s only for routers that have a wider range and also host 2.4GHz networks only.

Solution #3 Power Cycle Problematic AC

Instead of only fixing your thermostat, you should also pay attention to any problems that the AC itself has.

If everything is okay with the Nest thermostat, then the problem you’re having is most likely with the AC.

We will want you to power cycle the AC in order to fix the issue and here’s how to do it:

1. Unplug the AC from the power source.
2. Wait for 5 minutes while the AC is unplugged from power.
3. Reattach its adapter, back into the source.
4. Start the AC.
5. Test.

Note: Ensure that by the time you’re reconnecting the AC, your thermostat is running and you can test whether the issue is solved.

Solution #4 Replace Nest Battery

Your Nest thermostat’s battery has most likely come to an end-life and needs replacing.

In this solution, we will guide you through replacing the thermostat’s battery completely in detailed steps you can follow.

Here’s how to replace Nest’s battery:

1. Take the thermostat off the wall.
2. Grab hold of the thermostat’s front panel.
3. Pull it slightly towards you until the entire compartment comes off.
4. Expose the battery inside of your Nest.
5. Grab the same replacement model of battery.
6. Eject the old one and insert the fresh battery.
7. Reinstall your thermostat onto the wall.
8. Test.

Note: Mind how you insert the battery and which side of the battery faces what polarity.

Solution #5 Reset The Nest Thermostat

If none of our solutions were helpful so far, perhaps a factory reset on the Nest thermostat will be capable of fixing the issue.

Keep in mind that factory resetting your Nest thermostat will result in a total data loss.

Alert: Resetting the thermostat will erase all schedules, heating settings, and enabled features.

Here’s how to factory reset the Nest thermostat in easy-to-follow steps:

1. On your thermostat, tap the Quick View menu to open it.
2. Choose the settings icon.
3. Turn the ring once and select Reset.
4. Choose All Settings and select again.
5. Confirm if you want to proceed.
6. Wait for the factory reset to finalize.
7. Test turning on your AC.

Note: Do not interact with the thermostat while the reset is ongoing to avoid any further complications with the software.

Thus, to fix when Nest is unable to turn on the AC compressor, power cycle the thermostat and the AC as well. Move the router closer to the thermostat and replace the device’s batteries. Only then, proceed with a factory resetting your thermostat to solve the problem.

Read Next: Can You Use a Nest Thermostat Without WiFi?

Bottom Line:

We hope that now after finding out why is the Nest thermostat not turning on AC compressor, fixing the issue would be easy.

Don’t hesitate to reach out to Nest for external assistance regarding the problem or even contact an HVAC professional to check your configuration!

To find more of our content, visit the online technical blog we have posted and learn the solutions to all of your smart-home inquiries!