Nest Thermostat Not Cooling to Set Temperature: Fixes to Try

Is your Nest thermostat not cooling to the set temperature? I experienced the same issue recently.

Nest Thermostat Cooling Issues

In this post, I have carefully explained the steps I took to resolve the problem.

If your Nest Thermostat isn’t cooling to your set temperature, go to your circuit breaker and flip it off and back on.

If that doesn’t help, read on for more details on how to resolve this issue.

Turn On Your Circuit Breaker

If your Nest thermostat isn’t cooling your room to your set temperature, your circuit breaker might have flipped off. Perhaps, a power surge occurred while the thermostat was already cooling your room. This surge may have triggered your breaker, thus causing it to flip off.

Once your circuit breaker is off, all the power in your home will go out. Since your Nest thermostat can’t work without power, it will stop cooling.

To fix this issue, you’ll need to turn your circuit breaker back on. Go to your breaker and check if it is turned off.

If your circuit breaker is switched off, flip it back to the On position. Then wait for your thermostat to start cooling again.

If your Nest thermostat doesn’t cool to its set temperature after this, try the next tip.

Wire Your Thermostat Properly

Your Nest Thermostat may also fail to cool to its set temperature because you didn’t wire the device properly.

You can’t just place your HVAC wires in any terminal you want. Each wire on your HVAC system must be inserted into its designated terminal on the thermostat. Otherwise, the thermostat won’t work properly.

To resolve this problem, you’ll need to label your wires correctly and insert them into the matching terminal on the thermostat.

But before you can label your wires correctly, you’ll need to first understand your cooling system. This is because the appropriate wiring setup for your Nest thermostat depends on the type of cooling system you have.

What this means is that you need to determine whether your cooling system is an air conditioner or a heat pump. You can do this by checking the label on your cooling system.

If you don’t find any label on the system, look for the brand name and model number of the system in the owner’s manual. Then, enter these details on Google to determine the type of cooling system it is.

After identifying your cooling system, you should also confirm that the system is compatible with your Nest Thermostat. The Nest Thermostat only supports 24-volt cooling systems.

That said, there are some 24V cooling systems that are incompatible with the Nest thermostat. Examples of such systems are electric floor heaters, electric wall heaters, and cooling systems that use coal or wood to operate.

Once you’ve confirmed that your cooling system is compatible with the Nest Thermostat, you can start labeling the thermostat. You should have a picture of your initial wiring setup. This picture will show you all the terminals available on the original setup and the corresponding wire for each terminal.

Follow the steps below to label your thermostat’s wires correctly:

  • Turn off your circuit breaker.
  • Unmount your Nest thermostat’s display screen from the base.
  • Remove all the wires on the base. Then get some tape and tear it into pieces.
  • Study the picture of your initial wiring setup.
  • Write the name of each terminal on a piece of tape.
  • Using the wiring setup diagram, label your thermostat wires correctly with the pieces of tape.
  • After labelling your wires, visit Google’s Nest Compatibility Checker. The system will ask you to enter all terminals available on your original wiring setup.
  • Once you input this information into the Compatibility Checker, you’ll get a diagram that indicates the proper way to connect the wires to your Nest thermostat. Use the details in this picture to insert your wires correctly into the thermostat. 
  • Now, remount the thermostat’s display back onto the base. Then, turn on the circuit breaker and your thermostat and wait 30 minutes for the thermostat to cool to your desired temperature.

If your thermostat doesn’t reach your set temperature after 30 minutes, continue to the next tip.

Insert Your R Wire Correctly into Your Thermostat

Placing your R wire wrongly may prevent your Nest Thermostat from cooling to its set temperature. This problem occurs because while the Nest Thermostat has Rc (Red Cooling) and Rh (Red Heating) ports, most wiring setups only come with an R wire.

Nest Thermostat wiring

Some cooling systems only work when the R wire is placed in the Rh port. Other systems won’t work unless you insert the R wire in the Rc port. Since it’s hard to tell which category your cooling system belongs to, you may insert your R wire in the wrong terminal.

The only way to resolve this problem is to try placing the wire in the Rc and Rh ports and see if the thermostat starts cooling.

Here’s how to do that:

  • Flip off your circuit breaker.
  • Remove your thermostat’s display from its base.
  • If you’ve placed your R wire in the Rc port, remove it and insert it into the Rh port.
  • After switching the position of your R wire, replace your thermostat’s display and turn on your circuit breaker.

Your Nest Thermostat should work fine now.

Replace the Blown Fuse in Your Air Handler

Another major culprit is a blown fuse in your air handler.

Your air handler circulates the air from your cooling and heating systems around your home. So, if the air handler is defective, it might be unable to distribute the air from your cooling system evenly. As such, your room temperature may take a long time to match the set temperature on your thermostat.

You can fix this issue by changing the blown fuse in your air handler.

Follow these steps to replace the blown fuse in your air handler:

  • Flip off your circuit breaker.
  • Look for your air handler. Most air handlers are located in the basement or attic, and they often look like gas furnaces.
  • When you find the air handler, remove the cover and inspect all the fuses in the device.
  • Check for any blown fuses. Usually, blown fuses look blackened.
  • If you find any blown fuse, take it out and replace it with a new one. You can order a new air handler fuse online.
  • Finally, close the air handler and turn on your circuit breaker.

Now, wait for your Nest Thermostat to cool to its set temperature. If the thermostat fails to do so within an hour, try the next tip.

Reboot Your Thermostat

Sometimes, the cooling issue in your Nest thermostat may have nothing to do with the hardware. Rather, the thermostat might not be cooling properly because of a malfunction in the device.

Rebooting your thermostat should resolve this problem.

Take the following steps to reboot your Nest Thermostat:

  • Press the power button on your thermostat to turn it off.
  • Wait 5 minutes.
  • Now, switch on the device.

If the thermostat doesn’t cool to its set temperature after the reboot, proceed to the next tip.

Update Your Thermostat’s Software

If you’ve been using your Nest thermostat for a while, the thermostat’s system may slow down. Due to this issue, the thermostat may not operate as well as it used to. 

A software update should resolve this issue. Updating your thermostat’s software may eliminate the functional errors in the system, thus restoring the device to its normal state.

Here’s how to update your Nest Thermostat’s software:

  • Go to the home screen of your Nest thermostat.
  • Tap on Settings.
  • Then click on Version.
  • Choose Update.
  • If you are using the updated version of your Nest Thermostat software, you won’t see the Update option.

If you use a Nest E or Nest Learning thermostat, you can’t use the usual process for updating the system software.

Here’s how to update your Nest E and Nest Learning Thermostat’s software:

  • Navigate to your thermostat’s home screen.
  • Choose Settings and select Software.
  • Now, tap Update to update your thermostat’s software.

If your Nest Thermostat doesn’t cool enough after this, move on to the next step.

Adjust Your Temperature Schedule

You may have made a mistake while scheduling your Nest Thermostat to cool. Perhaps you set the device to lower its temperature by 5 pm when you wanted it to cool at 5 am.

In that case, you’ll need to adjust the temperature schedule on your thermostat.

Follow these steps to change your Nest Thermostat’s temperature schedule:

  • Go to the thermostat’s home screen.
  • Click on Thermostat.
  • Then, tap Settings.
  • Choose Schedule. You’ll see the days you’ve made schedules.
  • Click on the day you want to adjust. 
  • Select the temperature you’d like.
  • Change the time by sliding the numbers up and down.
  • Once you’re satisfied with the changes, tap on Done.

Nest Thermostat E and Learning Models

  • Click on the Quick View Menu on the thermostat’s home screen.
  • Tap on Schedule.
  • If you don’t find the Schedule option on the Quick View Menu, click on Settings. Then choose Schedule.
  • Scroll to the day you want to adjust.
  • Then tap on Change.
  • Rotate the ring on your thermostat to choose your desired time.
  • Tap on Done.
  • Turn the ring again to select the temperature you want.
  • Click on Done again to save the new setting.

If your Nest Thermostat doesn’t cool to the set temperature, don’t give up. The next tip might resolve the problem.

Move Your Thermostat Away from Sunny Areas

Did you place your Nest thermostat near a sunny spot in your home? Then, that might be the reason why the device isn’t cooling enough.

The heat in the sunny area may cause the thermostat to wrongly assume that your room is warmer than it actually is. As a result, the thermostat may expend all its power into lowering the assumed temperature. This might make your thermostat so weak that it can no longer produce enough cool air.

To fix this issue, you’ll need to move the thermostat away from the sunny areas and reinstall it in a cool spot. Also, avoid placing the device near windows, doors, your kitchen and your air vents.

Is your Nest Thermostat working properly now? If it isn’t, try the next tip.

Reset Your Thermostat

If none of the steps above fixes the issue, reset your Nest Thermostat. A reset may remove all the glitches affecting the thermostat’s functionality.

Please note that all your thermostat’s settings will disappear after the reset. That said, you can back up the settings you’ve made to your thermostat before resetting the device.

Here’s how to do that:

  • Click on Settings on your thermostat’s home screen.
  • Choose Equipment.
  • Then record your heating types and temperature settings.

Once you’ve backed up the settings, it’s time to reset the thermostat.

  • Follow these steps to reset your Nest Thermostat:
  • Press the ring on the thermostat.
  • Tap on the Quick View Menu and choose Settings.
  • Click on Settings and select Software.
  • Finally, rotate your thermostat’s ring to the Reset option.

Your Nest Thermostat should be able to cool to its set temperature now.

Wrapping Up

Ensure that you’ve tried all the steps above before resetting your Nest Thermostat. If you still face issues with your Nest Thermostat after the reset, contact Nest Support.

You may also like to see how to troubleshoot Nest thermostat charging issues and blank screen problems.