Nest Thermostat Not Turning on AC? Try These Fixes

Nest Thermostat Not Turning on AC

One issue that you may have is that your Nest Thermostat is not turning on the AC. This can become an issue if you live somewhere hot and it is the middle of the summer

In this article, I will be going over the most common reasons why this could be happening to your Nest Thermostat and solutions on how you can fix this issue.

Why is My Nest Thermostat Not Turning on My AC?

When your Nest Thermostat AC is not turning on, it could be for many reasons. Before you go and get a new Nest Thermostat or hire someone to fix it you can troubleshoot this yourself.

In this article I will be going over the reason why this could be happening from battery issues to rebooting your Nest Thermostat, and fixes you can do yourself. Read below to see why your Nest Thermostat is not turning on the AC.

1. Dead or Low Battery On Nest Thermostat

One of the most common reasons your AC is not turning on your Nest Thermostat is that your battery could be dead or even low. If the Nest Thermostat does not have enough power the AC will not turn on.

The battery could deteriorate over some time, leaving the AC to your Nest Thermostat not able to function properly. Over time the lifespan of a battery can end and lower the quality of the battery.

If the battery is low quality to begin with the AC will not work due to low power. The Nest Thermostat needs about 3.6 Volts to work properly, if the battery is not providing that then the AC will not work on the Nest Thermostat.

Fix – Charge or Replace the Batteries on Your Nest Thermostat

If the AC is not working on your Nest Thermostat and you have noticed that the batteries are either low or dead, this is one thing that you can do. The best thing to do is charge or replace the battery on your Nest Thermostat with a new one.

Here are 1.5v AAA batteries (view on Amazon) that are needed for your Nest thermostat.

Here’s how to replace it:

1. Pull the thermostat display off the base.

2. Remove the old batteries from the back of the thermostat display.

3. Insert the 2 new AAA alkaline batteries.

4. Push the thermostat display back onto the base until it clicks into place.

2. Your Nest Thermostat Wires Are Loose

When checking if your batteries did not work and replacing the old battery with the new one there are a few things to check. If the AC on your Nest Thermostat is not turning on, it could be because the wires have become loose over time.

In order for the Nest Thermostat to work properly all the wires must be connected correctly, if you have had your Nest Thermostat for some time now the wire could have become loose.

Note, that if you have never used your AC and it is not turning on it could be that the wires were not installed correctly.

Fix – Check the Wires on Your Nest Thermostat

In order to see if any wires are loose on your Nest Thermostat you will have to remove the thermostat from the wall. The wire that you are looking for is the RC wire (Red Cooling Wire), in order for your AC to work the RC terminal has to be connected.

Look the wires over to see if you can see any damaged or loose wires. However, if your Nest Thermostat has only one terminal marked “R”, this is a 24-volt hot terminal. You can check that terminal for loose or damaged wires as well.

There are three terminals that you can check the wires in as well, these terminals can cause issues with your AC.

The C terminal provides the power to your Nest Thermostat, the Y terminal controls the cooling relay in the condensing unit of the AC, and the G terminal controls the indoor blower fan relay.

You can check any of these terminals to see if there are any wires that you can tend to.

3. WIFI Router Is Not Connecting to Nest Thermostat

In order for your Nest Thermostat to work it needs to be connected to the internet. The Nest Thermostat needs to be connected to the internet to be able to control your applications, this means your AC too.

If you are having connection problems or your Nest Thermostat is not connected to an internet connection this can keep your AC from not working.

If you have a connection and it is not your network it could be that your WIFI router is too far from the thermostat. This can cause a broken connection between your WIFI router and your Nest Thermostat.

Fix – Move Your WIFI Router

If your AC is not working on your Nest Thermostat it could be an internet connection issue. If your WIFI router is out of range of your Nest Thermostat it can cause your thermostat not to work, including your AC.

The best thing to do is move your WIFI router near the thermostat to ensure that the internet is connecting to your Nest Thermostat. Once you have a good internet connection try using your AC once more and see if it was a connection issue.

4. Nest Thermostat Needs to Be Rebooted

One way to determine that your Nest Thermostat needs a reboot is to see if the thermostat voltage is too low. On a Nest Thermostat, it needs no less than 3.6 volts of power, if your thermostat is lower than that you might want to do a reboot on your Nest Thermostat.

To see the voltage quality go into the settings on your Nest Thermostat display. Once you are in the setting you will go into the “Device Information” and select power.

Once you tap on the power option you will then select the “Battery Label”, when you are there you will be able to see the voltage quality.

Fix – Reboot Nest Thermostat

If you have determined that your Nest Thermostat needs to be rebooted, follow these steps below.

Press and hold the Nest Thermostat ring for 10 seconds.

When you see the screen go blank then release the hold on the Nest Thermostat ring.

Press on the Nest Thermostat once more to turn on your thermostat.

When your Nest Thermostat restarts you will see the Nest logo on the screen. When this appears your Nest Thermostat will be rebooted.

5. Nest Thermostat Not Reading Room Temperature Correctly

When you are having issues with your Nest Thermostat AC not turning on it could be that your thermostat is not reading the temperature of the room right. This can happen if you are running the HVAC continuously throughout the day.

Having your HVAC running all the time throughout the day can stop your AC from turning on because it is reading the room’s temperature wrong. There is a way you can stop your HVAC from running constantly.

Fix – Set Nest Thermostat HVAC to Auto

When your HVAC is running through the day this can cause the thermostat to read the room’s temperature wrong, making your AC not turn on.

Your thermostat will turn on your AC automatically when you set all the systems in your HVAC to “Auto”, when you turn the HVAC on auto it will only come on when the temperature of the room rises or lowers from the temperature you set it to.

The HVAC includes a heater, boiler, fan, and AC, when it is on auto it will either turn the heat or AC on when needed due to what the temperature in the room is.

6. Nest Thermostat Is Dirty

An issue that can cause your thermostat AC to not turn on is that your thermostat is dirty, when dust and dirt accumulate on your Nest Thermostat it can cause the efficiency to be reduced.

If your thermostat has become too dusty this can cause a power issue, if the electric supply is not sufficient this can keep your AC from operating. Thankfully this issue can be resolved.

Fix – Clean Nest Thermostat

If you have had your Nest Thermostat for a while there could be a chance that dust is preventing your AC from turning on due to the dusty environment.

This can cause your thermostat to require more power to function, causing the AC to not turn on. There are two ways you can clean your Nest Thermostat once you have removed the thermostat faceplate.

One way is using compressed air in a can, the can spay any dust off the wires and in tight places a cloth can not get to. The second way is to gently wipe off the dust by using a soft cloth or brush.

When your AC is not working on your Nest Thermostat it could be because of multiple different reasons. As said above, before you spend money on replacing your thermostat with a new one or hiring someone to fix it, try fixing the issue yourself.

Who knows it could be anywhere from a battery issue to the thermostat needing to be rebooted. Whatever the technical issue may be if this guide has helped you in any way share this with your friends and family who also own a Nest Thermostat.

7. Replace Nest Thermostat Or Contact Support

If you have checked the battery isn’t low, the wires aren’t lose and the WiFi is connected, the tried all of the other small fixes, and it still won’t turn on your AC, it’s time to either replace your Nest Thermostat.

I personally use the Nest Learning Thermostat, which I picked up from Amazon.

Or contact Nest Support.

Note: Only pick up a new Nest Thermostat if you’re convinced the one you currently have has too many issues. There’s no point in picking up a new thermostat if the problem with your current thermostat can easily be fixed.

Brady Klinger-Meyers is an experienced writer and marketer with who currently writes for Robodens as well as other popular sites like MakeUseOf and Techzillo. At Robodens, he focuses on general smart home advice with his interest being accessories and gadgets. Read our Editorial Guidelines and Fact Checking process.


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