Nest Thermostat Not Cooling (You MUST Double Check The Wiring!)

Please tell me if you own a Nest thermostat at your home that isn’t working correctly. If the device is not cooling, or worse, if it is blowing hot air while it must be blowing cold air, there are a few possibilities.

Troubleshooting is a good place to begin, regardless of what the issue is.

In most circumstances, a rewiring will be necessary to remedy the problem.

How to Troubleshoot a Nest Thermostat That Isn’t Cooling

Using the “Conventional” label on your previous thermostat instead of the “Heat Pump” label is why your Nest thermostat isn’t cooling. Replacing your existing thermostat with a Nest that uses the Heat Pump side will take care of the problem.

Mislabelled Thermostat Wires

If you suspect that you may have mislabeled your cables because you misdiagnosed your cooling system, continue on.

Identify Your Home’s Heating and Air-Conditioning System

Determine the sort of cooling system in your property before anything else.

This is the quickest and simplest approach to do so. If it’s a heat pump or an air conditioner, there must be a label on it.

The brand name and model number may also be seen on the gadget, so you can Google the system to find out additional information.

In addition to turning on the heat, you can also check the exterior system by turning it on. If it does, then you know you have a heat pump in your home.

My best guess is that you have a heat pump system, but you mistook it for a traditional one.

Relabel Old Thermostat Wiring

Depending on the sort of cooling system you have, it’s probable that you’ll want to rename your thermostat wires.

Make sure to save any photos or diagrams of your previous thermostat’s wire arrangement in order to use them as a guide. Assuming that’s the case, you may just rename your wires with the Heat Pump row from the picture (for example).

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Google’s free Nest thermostat compatibility checker may be used to verify that your cables are labeled appropriately.

Using this data, the compatibility checker will build the proper Nest wiring for you to utilize when setting up your device.

Nest Thermostat Rewire

Ensure that the Nest is completely unplugged before you begin rewiring it.

When working on the wiring, it’s advisable to switch off the circuit breaker in that room.

You’ll need to remove your Nest’s display screen in order to separate and reconnect wires depending on the schematic given by the compatibility tester.

The Nest cables should be secure and free of kinks after they’ve been attached to the correct locations.

Replace your Nest display screen and switch the circuit breaker back on after you’re finished.

After a few minutes, you should be able to get your Nest back up and running!

Tripped Circuit Breaker

Try checking your circuit breaker box for tripped fuses if you still have problems with cooling.

In order to achieve this, all you have to do is check for any switches that are turned off.

Flip the breaker on, off, and then back on again once you’ve located the problem.

Your problem may be solved by doing this.

The RC and RH Wiring Problems.

Metal is used to connect a R wire to an RC or RH wire in certain vintage thermostats. It’s quite simple to overlook.

RC and RH cables are separated into their own ports in Nest, though. Nest’s RH port should be used if you only have one red R wire.

You may try to connect the red wire to your RC port instead if that doesn’t work for you.

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Inside the Air Handler, there was a blown fuse

It’s possible that a blown fuse in your air handler is to blame for your Nest’s inability to cool.

The removal of numerous screws may be required to remove the lid of the air handler in order to access this fuse.

You’ll notice a circuit board with a few fuses once you go inside.

If you don’t know which one has blown, you may just replace all of them.

Tips and Tricks for Troubleshooting

Even after you’ve gone through all of these steps, you may still be experiencing cooling difficulties.

Check Your Cooling System’s Compatibility with Nest.

Nest may not be able to communicate with your cooling system.

High voltage or solid fuel systems, for example, are not compatible with Nest. In certain cases, the Nest may not be able to function with the cooling system in your house.

Your previous investigation should make this decision a piece of cake.

Even yet, here’s a list from Google detailing which thermostats are not compatible with Nest.

Begin a System Reboot

If your Nest thermostat isn’t cooling, it’s still worth resetting the thermostat to see if it fixes the problem.

There are a number of ways to do this, such as turning off the Nest’s fuse or reducing the Nest’s electricity in some other method.

Wait five minutes before re-activating the Nest.

For a few minutes, you’ll need to sit back and wait for the Nest to reboot and reconnect to your home’s other systems.

Manually resetting the device is another option:

  • To access the Quick View menu, just press the thermostat ring on the device’s ring.
  • Choose Settings .
  • Turn the ring to the Reset position and click the select button to activate.
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Remove and Reinstall Your old Thermostat.

Assuming you’ve made it to this stage, you’ll want to make sure that the Nest isn’t the problem with your cooling.

Reinstalling your previous thermostat is one option.

You’ll want to switch off the thermostat’s fuse first before tinkering with any wires.

By reinstalling your old thermostat, you may check to see whether there is a problem with your home’s wiring. There is a problem with the Nest if the old thermostat works perfectly but the new one doesn’t.

It’s possible that the wiring for the cooling system is faulty if the old thermostat doesn’t work. In most cases, a professional electrician should be called in.


There are four frequent reasons why your Nest thermostat won’t chill your home:

Inaccurate thermostat wiring labels

Circuit breaker was tripped.

Problems with the wiring of the RC and RH

Inside the air handler, a blown fuse.

There are some more things you may try if none of the above work:

Make sure your cooling system is compatible with Nest.

Restarting your Nest.

Install your previous thermostat again.

Call a professional if all of the above fails to solve your cooling problems. All of the problems in your wiring will be spotted by them. They’re also capable of doing the task in a safe manner.

Is your Nest thermostat working as it should? If so, please tell us how it went in the comments below!

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