Nest Thermostat Not Cooling: How to Troubleshoot

If your Nest thermostat isn’t cooling and you’re not sure how to go about the issue, keep reading.

In this post, we’ll walk you through some handy tips to troubleshoot this problem. Let’s dive in.

Nest Thermostat Not Cooling

First off, here are some reasons your Nest thermostat isn’t cooling:

  • Your air handler has a blown fuse.
  • The thermostat is incompatible with your HVAC system.
  • You mounted your thermostat in the wrong place.
  • You set your thermostat to cool at the wrong time.
  • Your Nest thermostat’s firmware is outdated.

Now, let’s look at how to get this fixed.

How to Troubleshoot Nest Thermostat Cooling Issues?

So here are some troubleshooting steps to try:

1. Check and Flip On Your Circuit Breaker

Your circuit breaker may trip due to a power surge. When this happens, the power in your home will go out. This will prevent your thermostat from cooling.

If your Nest thermostat suddenly stops cooling, check if your circuit breaker is turned off. If the breaker is off, flip it on. This will restore the power in your home. And your thermostat may start cooling.

If your Nest thermostat doesn’t cool after you’ve turned on your circuit breaker, try the next troubleshooting step.

2. Reboot Your Thermostat

Your Nest thermostat may not cool because of a malfunction in the device. The fastest way to fix functional issues in your Nest thermostat is to reboot the device.

You can reboot your Nest thermostat by long pressing the thermostat ring until the screen turns off. Now release the ring, then press and release the ring again to turn on the screen.

That’s all you need to do to reboot your Nest thermostat. And this should fix the cooling problem.

However, if the problem persists, try the next tip.

3. Check Your Thermostat Wiring

If your Nest thermostat isn’t cooling, you may not have inserted your wires correctly. This tends to occur when you misidentify your cooling system.

Why does this matter? Your cooling system can either be an air conditioner or a heat pump. These systems have different wiring setups.

So, if you identify a heat pump as an air conditioner, you’ll label your wires wrongly. This also means that you will insert the wires in the wrong terminal in your thermostat. Because your cooling system’s wire is incorrectly placed in the thermostat, the device won’t be able to cool.

Here’s how to fix this problem:

  • Turn off your circuit breaker.
  • Remove the display screen on your thermostat. Then detach all wires from your Nest thermostat.
  • Check if your cooling system is a heat pump or air conditioner. You can do this by turning on the heat in your home. If the cooling unit outside your home starts working, you are using a heat pump.
  • Next, search for the wiring setup for your old thermostat.
  • Relabel your wires according to the wiring setup for heat pumps.
  • Once you’re done labeling your wires, enter the setup into the Google Nest compatibility checker.
  • The compatibility checker will use this data to generate the appropriate wiring diagram for the thermostat.
  • Insert your wires into the thermostat as shown in the diagram. Ensure that these wires fit snugly into the terminals on your thermostat.
  • After inserting all the wires into your thermostat, put the display screen back on the device.
  • Turn on your circuit breaker.

Your Nest thermostat should boot and start cooling after this. However, if the device doesn’t cool, proceed to the next tip.

4. Insert Your R Wire into the RC/RH Terminal

Your Nest thermostat may not cool because you placed your R wire in the wrong terminal. If you have 2 R wires, please skip this step.

Your thermostat contains matching ports for all your wires except the R wire. Instead of an R terminal, you have RC and RH terminals. This might make you confused about where to insert the R wire.

While using your old thermostat, you probably used a jumper to connect your R wire to your RC and RH terminals. But the Nest thermostat doesn’t support jumper wires.

Knowing this, you might have inserted your R wire into the RC or the RH terminal and turned on your thermostat. Nevertheless, your thermostat may not support inserting your single R wire into the terminal you’ve used.

Some Nest thermostats require that you place the R wire in the RC terminal. However, others will only work if you insert the R wire in the RH terminal. The only way to find the correct port for your R wire is to try inserting the wire into both terminals and see how they respond.

If your R wire was originally in the RH terminal, place it in the RC terminal. Then, turn on your Nest thermostat.

Your Nest thermostat may cool now. However, if your thermostat fails to cool, continue to the next tip.

5. Replace the Blown Fuse in Your Air Handler

The air handler in your home blows hot and cool air around your home. But if one of the fuses in the air handler gets blown, the device will stop working. If your air handler isn’t working, your thermostat won’t turn on the AC.

If your Nest thermostat isn’t cooling, you’ll need to check if your air handler is in good condition.

Most air handlers are located in the basement or garage. Once you find the air handler, open it up and inspect it for any blown fuses. Usually, fuses turn black when they get blown.

If you see any blackened fuse, remove it and replace it with a new one. You can order another fuse online.

Your Nest thermostat may start cooling after you’ve changed the fuse in your air handler. But if the thermostat isn’t cooling, try the next tip.

6. Check if Your Thermostat is Compatible with Your HVAC System

Your Nest thermostat won’t cool if it is incompatible with your HVAC system. The thermostat supports most devices except proprietary and high-voltage systems.

A proprietary system only works with thermostats made by its manufacturer. That said, you can make your proprietary system work with your Nest thermostat by rewiring it.

High-voltage systems require a high amount of voltage to function. These systems are often labeled with 115, 120, or 240 VAC. To make your high-voltage system compatible with your Nest thermostat, you’ll need to set up a step-down transformer in your home.

Once you’ve made your HVAC system compatible with your Nest thermostat, the thermostat may start cooling. But if you discover that the thermostat isn’t blowing cool air, continue to the next tip.

7. Move Your Thermostat to a Cooler Spot

Installing your Nest thermostat near extremely sunny or cold spots in your home can prevent the device from cooling. Examples of such areas are windows, doors, and hallways.

Exposing your thermostat to sunlight or cold can weaken the device. As a result, the device may stop functioning properly.

To fix this issue, remove your thermostat from the exposed area and move it to a cooler spot. You can re-install your thermostat in your living room or dining room. These areas are great locations for your thermostat because they often retain room temperature.

Your Nest thermostat should start cooling after you’ve re-installed it in a cooler spot.

However, if the device isn’t cooling, try the next tip.

8. Check Your Cooling Schedule

Did you set your thermostat to cool at a particular time? Then you might have made an error while setting the time. Perhaps you set your thermostat to cool at 5:30 pm when you wanted to schedule it for 3:30 pm.

If your Nest thermostat isn’t cooling, check your cooling schedule to ensure that you entered the correct time.

Here’s how to check the cooling schedules on your Nest thermostat:

  • Press the ring on your thermostat to open the Quick View Menu.
  • Click on Settings. Then select Schedule. You’ll see all the cooling schedules you’ve set on your thermostat.

If you’ve set your thermostat to cool at the wrong time, you can change it on the Schedule screen.

However, if checking your cooling schedule confirms that you set it correctly, move on to the next step.

9. Update Your Thermostat’s Firmware

Your Nest thermostat may not activate cool if its firmware is outdated.

Usually, the thermostat’s firmware updates itself automatically. However, the firmware update might have failed due to connection issues.

You can resolve this issue by updating the thermostat’s firmware manually.

Follow these steps to manually update your Nest thermostat’s firmware:

  • Open the Quick View Menu.
  • Click on Settings. Then select Version.
  • Next, select Update.
  • Your thermostat’s firmware will start updating.

Next, wait a few minutes for the update to be complete. Your thermostat should start cooling after this.

But if your room still feels hot after several minutes, go to the next tip.

10. Factory Reset Your Thermostat

If your Nest thermostat won’t cool after trying all the fixes above, you can try factory resetting the device. This usually helps to fix internal glitches or incorrect settings preventing the devices from turning on the AC.

However, note that factory resetting your Nest thermostat will delete all the settings you’ve saved on the device. You’ll need to set it up again as you did when you first installed.

Take the following steps to factory reset your Nest thermostat:

  • Open up the Quick View Menu by pressing the ring on your thermostat.
  • Tap Settings. Then select Reset.
  • Now, select All Settings to factory reset your device.

Wrapping Up

If your Nest thermostat isn’t cooling, flip on your circuit breaker and wire your thermostat correctly. You might also need to insert the R wire in the RC or RH terminal.

If the thermostat doesn’t cool after this, check and replace any blown fuse in your air handler. Then check if your thermostat is compatible with your HVAC system.

Moving your thermostat to a cooler spot should also fix this issue. In addition, you’ll need to check if you set your cooling schedule correctly.

Other ways to resolve cooling issues in your thermostat include updating your thermostat’s firmware and rebooting the device. Factory reset your thermostat if these solutions don’t work.

However, if your Nest thermostat fails to cool after you’ve applied all the steps above, contact Nest Support.

You may also like to see how to troubleshoot heating issues in a Nest thermostat and Wyze Thermostat.