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Nest blowing hot air instead of cold

Nest blowing hot air instead of cold. Does your Nest thermostat blow hot air instead of cold at home during hot days? I can understand how annoying and disappointing you feel when the Nest thermostat does not cool the room even when it is set in cool mode.

Nest thermostats are the most popular in the industry; that saves your time in controlling the room temperature and are more efficient than the standard AC remote. However, sometimes it stops performing due to multiple different reasons.

In this article, I will walk through the reasons why your Nest does not cool the home properly and also discuss its troubleshooting tips to fix it.

Nest blowing hot air instead of cold

Nest blowing hot air instead of cold 2023

Although Nest thermostats are one of the best smart gadgets that easily control the room temperature, but it also induces problems.

Before jumping towards solution tips, you should recognize the causes and reasons why your Nest has stopped cooling.

  • Insufficient volts or not enough power supply
  • Damaged or dead battery
  • Incorrectly labelled wires
  • Dirty air filters
  • Blown fuse
  • Faulty compressor
  • Blocked or leaking air duct
  • Loose wiring inside the thermostat
  • An issue with the C-wire
  • Tripped or faulty circuit breaker
  • Unresponsive motion sensor

Let’s discuss some reasons in detail with their best possible solution.

Wrong Identification of Cooling System

The major reason for the thermostat cooling issue is the wrong identification of the type of cooling system. This will lead to the incorrect connection of wires.

Incorrect or loose wiring causes your Nest thermostat not to blow cold air in the home. For example, if you have a heat pump system and you set the wires like a conventional one.

How to Fix?

Honestly, the first thing you should check is the type of cooling system that you have in the home. It is essential to make sure that you set the wires according to your cooling system. You can check this by considering the following steps:

  • Select heat mode on your Nest thermostat.
  • Check if the unit is running; you definitely have a heat pump system.
  • Increase the temperature unless the thermostat sensor turns orange.
  • Wait for 10 minutes after it is working.
  • Then invert the process and set the Nest thermostat into cool mode.

Remember, when the O/B-W wire is orange, it will be the heat pump system; if it is white, it will be the conventional system.

Incorrect or Loose Wiring

Nest Thermostat Incorrect or Loose Wiring

The incorrect or loose wiring causes your Nest thermostat not to blow cold air during summer. If you connect Rh, W1, W2, Y1, and Y2 in the wrong manner, it will lead to your air conditioner stopped cooling.

C wire is vital in the thermostat, which helps to draw power from the HVAC system. Any damage in the C-wire is also the reason for the improper function of the Nest.

Quick Tip

To solve the Nest cooling problem, you should make sure that you connect the wires properly and correctly. Rewire if any connection is loosed or damaged. Ensure that you accurately connect RH for power, W1 for heat, Y1 for cooling, and C for common wire.

So, insert the Y wire wisely to fix the thermostat cooling problem.

Tripped Circuit Breaker

Is your Nest not cool the room completely? If there is no problem with the thermostat’s wire connection, it might be possible there is an issue with your circuit breaker.

The tripped circuit breakers and switching off the circuit box will cause the thermostat to stop functioning. Your thermostat breakers may trip because of the following reasons:

  • Short circuit
  • Overloaded circuit
  • Ground fault
  • Loose connections

What to Do?

Let’s have a look at the tripped breaker solution for the problem in which the Nest blows hot air instead of cooling.

  • Check the circuit breaker box by opening it carefully.
  • Start resetting the breaker box by switching on the buttons.
  • Then turn off the breaker and switch it on
  • Try to stand on the side of the breaker as a precautionary method.

You should call the electrician if this method does not prevent your circuit breaker from tripping.

Blown Fuse

Nest Thermostat Blown Fuse

Another reason for the Nest thermostat not running the AC properly is the blown fuse in the air handler.

When your air conditioner does not make any sounds or pull air from the outside, then the fuse will have a problem.

Best Possible Solution

First, check the blown fuse by opening a tiny circuit with the screwdriver. Ensure to replace the blown fuse from an expert. Fuses are cheap items, so if you don’t find a blown fuse, consider replacing all the fuse.

Low Battery Signal and Disconnecting Wifi

Your Nest fails to cool the home because the battery level drops very low. A low battery status or dead battery will not allow the thermostat to control and regulate the cold temperature. A minimum battery signal causes the thermostat to be offline and disconnects the Wifi.

How to Fix?

You can check the battery status by opening the Nest app. However, a low battery problem can be solved by adding a C wire to give the thermostat battery a little more voltage. Below are the easy steps to connect the Wifi perfectly in your Nest:

  • Press the ”Menu” button on the Nest.
  • Then select the Wifi from the ”Settings”.
  • Select ”Network” and connect it by clicking ”confirm”.
  • Follow the instructions to stay online.

How to Factory Reset Nest Thermostat?

A factory reset solves almost many thermostat problems. You can easily do a factory rest by yourself when the Nest thermostat is blowing hot air instead of cold.

Follow the below steps to factory reset your device:

  • Install a ”NEST” app on your mobile phone and open it.
  • Add in your home screen.
  • Find the ”Quick View” menu and press it.
  • Click ”Settings” and search ”reset”.
  • Choose the ”Reset”.
  • Press the ”Restart”.


I hope my guide is helpful for you in solving the Nest thermostat not cooling issue. Now you can successfully fix the Nest when it blows hot air on the cool mode. I suggest you to clean the dirty air filters and evaporator coils. Don’t forget to connect the thermostat wires correctly.

In the end, I will say that the Nest device is the best device that offers you two year warranty. If you still have cooling problems with the Nest thermostat, you must check it to a professional.

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