Nest Thermostat Not Cooling? Causes & 6 Ways To Fix It

A Nest thermostat that isn’t starting the cooling system isn’t necessarily broken. In fact, this is one of the most common issues with the Nest thermostat in general, and it can be easily solved.

The first topic that we’ll discuss in this guide is how to successfully perform Nest thermostat troubleshooting, which will help you detect the issue, and hopefully, find a permanent solution.

Don’t worry, we’ve also got you covered with quick and easy solutions that you can try at home to get the cooling system to work again.

Why is the Nest thermostat not cooling?

An important fact about the Google Nest thermostat is that the temperature doesn’t need to be manually adjusted. This smart thermostat remembers your preferences and desired temperatures for a particular period of the day.

The Nest thermostat allows you to control your HVAC system (heating, ventilation, and air conditioning) without having to make the adjustments yourself. All you need to do is select the program (desired indoor temperature, cooling, or heating regime), and the smart thermostat will do all the work for you.

This way, you don’t have to worry about monitoring and adjusting the temperature yourself, since your Nest learning thermostat, thanks to its innovative technology, will do it for you.

The thermostat ring, however, allows you to adjust the temperature in case you’re not satisfied with its schedule, or you’d simply like to make some changes.

The Nest sense technology uses special temperature sensors, as well as motion and light sensors, and a humidity sensor to create the perfect temperature for you, while also factoring in the weather in your area.

However, it is possible even for smart thermostats to act up and not respond to the commands or not detect the room temperature correctly.

Keep on reading to find out why your Nest thermostat won’t start cooling.

1. WiFi connectivity problem

As you probably already know, your Nest thermostat requires WiFi to be able to get information about the weather in your area.

What’s more, without a WiFi connection, you will not be able to connect to your programmable thermostat through the Google Nest thermostat app.

Now, the WiFi problem could concern the WiFi service in your home, but it could also indicate an issue with the Nest service.

In some cases, certain technical issues, such as a damaged or missing C wire could affect internet connectivity, as well.

In case you notice a blinking green light on your smart thermostat, this usually means that the system is undergoing an updating process, which can sometimes cause Nest thermostat issues. However, once the updates have been installed, the green light should not keep blinking on your thermostat display, and the cooling system should work in your smart home.

If this is not the case, there could be a problem with the updates, or there is an entirely different issue affecting the cooling function.

2. Temperature extremes

While your smart thermostat should have a set safety temperature and never reach temperature extremes, in the event of a broken or missing C wire, the system may not be able to start the cooling system.

In this case, you will probably notice a low battery warning on the Nest thermostat screen, as well as a message about system overheating.

Keep in mind that, unlike your old thermostat, the Google Nest thermostat does not use AA batteries, but a lithium-ion battery that is powerful enough to keep running the system, and is also rechargeable.

3. Faulty sensors

As we’ve mentioned in the beginning, your Nest thermostat includes a number of sensors that the Nest sense system relies on.

In case any of these sensors is malfunctioning or damaged, this will affect all the functions of your thermostat, including cold air and heating.

Before you assume that there is something wrong with the sensors, check if your thermostat is installed close to the window. This kind of placement of the thermostat in your smart home could affect the temperature sensor.

Also, this smart thermostat should not be located near any heat source, since this may disrupt the signal and the connectivity between the thermostat and the Nest app.

As long as the thermostat is connected to the app, you should be able to see if any of the sensors are blocked or failing.

4. Improper wiring

A lot of the time, the main issue with your cooling system lies in the thermostat wiring. This is precisely why it is recommended to label the wires when installing your thermostat so you know exactly what could be the issue in situations like this.

In case there is a damaged or loose wire in your system, the thermostat will not be able to function properly and get your air conditioning to the desired temperature.

Speaking of thermostat wiring, it is possible for the common wire (also known as the C wire) to be disconnected or even damaged in some cases.

Since the common wire is responsible for the continuous power flow to the thermostat, a compromised common wire could result in the thermostat acting up, and not just when it comes to the cooling system.

5. Auto-schedule issue

Your smart thermostat is supposed to manage the temperature based on the sensor activity and the data from the weather app for your area.

However, if there is no cold air coming from your AC at night or whenever the cooling system is supposed to be turned on, this is usually a clear indicator that the auto-schedule option on your Nest thermostat is off.

What’s more, in case the eco-friendly program is enabled on your Nest app, the thermostat will not be able to control the temperature and the cooling system automatically, as with this mode the temperature is controlled remotely.

6. Nest thermostat compatibility

While this is something that should ideally be considered before even installing your Nest thermostat, you may notice that the thermostat is not compatible with certain parts of your HVAC system only after installing the Nest.

If your new thermostat is not compatible with the cooling system, this is precisely why the cooling option doesn’t seem to be working.

It is also necessary for your Nest system to receive the updates timely, as not installing the newest updates for your system may also create compatibility issues. In your Nest app, you should always be able to check for the latest version of the software so you can keep the system up to date.

How to fix a Nest thermostat that is not cooling

Your Google Nest thermostat system should control the entire HVAC system in your smart home, including the air conditioner. If you encounter some difficulties, it is necessary to troubleshoot the Nest thermostat before finding an adequate solution.

We’ve talked about the most common issues you may encounter with your Nest system, so here’s what you can do to fix the thermostat and start up the cooling system again.

1. Reset the thermostat

Sometimes, the easiest and quickest fix also proves to be the most efficient! If your AC isn’t turning on according to the Nest schedule, and the screen is blue to indicate cooling but there is no cold air coming out of it, you may need to reset the system.

You can do so by pressing the switch on the fuse box. After doing so, the cooling system should start up. However, if this trick didn’t work, you should keep searching for the core issue.

2. Test the wiring with your old thermostat

This is one of those situations where you’ll be so thrilled not throwing away the old appliance. The best way to test the wiring is to reinstall the old thermostat and check if the cooling system is working.

If there are no issues with the cooling system with your old thermostat, the issue may be in the Nest thermostat wiring.

However, if the cooling still doesn’t work after you’ve replaced the thermostat, you should contact a technician and have them take a look at your HVAC system, especially the AC unit.

3. Use a common wire system

Using a common wire (C-wire) system with your Nest thermostat is the best way to ensure there will be no compatibility issues with your new thermostat and the components of the HVAC system.

In case you already own a common wire system, and the cooling is still not working, you should open up the thermostat so you can access the wiring and inspect the wire in the C connection.

If you detect a wire, unplug it and wait for a few minutes before plugging it back in, ensuring that it is properly secured. If you notice any damage to the wire, you should replace it with a new one as soon as possible.

4. Inspect the wiring

The C wire isn’t the only element that requires a detailed inspection in case the cooling system won’t turn on.

Another possibility is that the wiring wasn’t installed properly in the first place. In this case, the easiest way to check if every wire is plugged into its respective outlet is to take a look at the manual.

You will need to turn the power off before accessing the wires in your Nest thermometer for your own safety, but also to prevent any damage.

Remove the display cover and check all the connections. Keep in mind that every single wire should be facing down. Now check where each wire is inserted and if all the connections have been properly installed.

Needless to say, any damaged connections or loose wires should be removed or tightened and secured, depending on the situation.

5. Factory reset

In case none of the methods turn out to be successful, you may perform a factory reset on your Nest thermostat to completely erase and reset all the adjustments and settings.

The easiest way to perform a factory reset is through your Nest application, so make sure you’re logged in with your account credentials.

Select your location if the app is connected to several locations, and then find the Nest thermostat account you’d like to reset.

Tap on the thermostat account, and then choose “settings” in the upper right corner. Scroll down until you see a “confirm thermostat” button, and click to confirm.

6. Adjust the temperature

In some cases, you will have to reset or adjust the temperature manually on your Google Nest thermostat if the cooling system isn’t starting up automatically.

Launch the Nest app on your smartphone. Navigate to the top left corner and tap on the three dots.

Find your Nest account, and ensure that the heat and cooling mode is enabled. Choose to “hold the temperature,” and then set the desired temperature manually on your thermostat. 

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