Nest Thermostat Cycling On and Off


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The Nest thermostat is one of the top smart thermostat manufacturers, but it’s not without occasional issues. 

Some people report that their Nest thermostats cycle on and off frequently, which will cause inconsistency with the temperatures. How often does your Nest thermostat cycle on and off?

Common reasons for Nest thermostats cycling on and off include having an old wire connected to them, using dead batteries, a blown fuse, or software issues. To solve these issues, you need to replace the battery pack, rewire everything, change the fuses, and update the Nest thermostat’s firmware.

This article will cover the reasons for the Nest thermostat cycling on and off and various solutions on fixing the cycling issue. 

1. Old Wiring System

Check your wiring first if you see your Nest Thermostat cycling on and off over a period of time. Loose connections from old wires in the house could be the cause. You should also check your HVAC equipment wiring as well.

A loose wire disrupts the flow of electricity to and from the Nest thermostat. The Nest thermostat’s C-Wire (common wire) gives the Nest its power from the HVAC equipment or the home’s main supply line. 

Because the design of the Nest Thermostat prevents it from drawing too much energy from the wall socket, bad wiring could cause the device to draw an excessive amount of electricity when charging its batteries.

That may lead to your thermostat not recharging correctly. Eventually, it could lead to the thermostat’s batteries draining too quickly, forcing a need to recharge it more often.

You will need to replace or rewire the electrical connection between your Nest thermostat and the heating/cooling system. It could also be the C-wire, so you may need to replace it.

2. Old or Worn Out Batteries

Nest Thermostat comes with an internal battery that powers its interface from the C-wire. If the battery wears out quickly, you need to replace it regularly. When the battery level is low or runs out, Nest Thermostat shuts down unexpectedly.

There are also backup batteries in case there’s a power outage. The Nest thermostat cycles on and off if either of the batteries go dead. You need to change the batteries to fix the issue.

Batteries wearing out quickly will make it feel like the Nest thermostat is cycling off and on, but it’s an easy fix to replace the batteries with new ones.

To replace the batteries, you must first remove the device from the wall. Then identify the location of the old battery. Finally, remove the old batteries from their sockets and replace them with two new ones.

Learn more about Nest Thermostat Battery Problems and Fixes.

3. Faulty Fuses

Fuses are used to protect the Nest thermostat from damage due to overloading.

A faulty fuse is one of those things that you wouldn’t think could be an issue with a Nest thermostat. It’s rare, but it can happen. 

When this happens the thermostat doesn’t work properly. You’ll probably notice that the temperature changes randomly, or the thermostat keeps turning on and off.

Cycling on and off usually occurs because the fuse isn’t tightly fitted into the fuse box. 

If the Nest thermostat won’t turn on at all, it could be that the fuse is blown. 

 To fix a fuse, you must first identify which fuse is faulty. Then, you must replace the fuse with a new one.

4. Direct Sunlight or Heat May Affect the Thermostat

The Nest thermostat is sensitive to direct light and heat. If the thermostat is in the way of a heat source or sunlight shining directly on it, it will cause the thermostat to think it’s overheated and shut down to protect itself. 

That will lead to constant cycles of on and off. It will also cause the temperature readings to be inaccurate. Your Nest thermostat is malfunctioning because it was exposed to too much heat.

To fix this issue, you need to move your Nest away from direct sunlight and heat sources. 

Also check the wiring and base of your Nest thermostat to see if there is any additional damage that needs to be fixed.

5. HVAC System Issues

The Nest Thermostat connects to the HVAC system, so if there are issues with the HVAC, the thermostat will also have issues. 

In most cases, the common problems is when the Nest Thermostat doesn’t draw enough power from the HVAC system. You can diagnose whether the system needs maintenance or whether the issue originates from the thermostat itself.

Follow these troubleshooting steps to diagnose the problem with a different smart thermostat:

  • Turn off the furnace by unplugging the unit from the wall outlet.
  • Disconnect your system from the power line.
  • Remove your current thermostat from the wall.
  • Connect the other thermostat to the HVAC equipment and power it on.
  • If the other thermostat also keeps cycling on-and-off, chances are your HVAC system is faulty.

You should contact an HVAC technician to repair the heating and cooling system. 

However, if the thermostat works fine after replacing it, then you might want to check the wiring.

6. Nest Thermostat Bugs and Software Issues

Like most electronics, Nest thermostats can have software issues and bugs, but they’re nothing new.

Different bugs will cause different resulting effects, including the thermostat to cycle on and off. The cycling will affect the charging of the battery, and make it drain the battery faster than it should.

After an incomplete or faulty software upgrade, these issues may arise.

Google Nest will usually fix software bugs quickly, so software updates on the Nest thermostat will eventually fix the bugs. You should manually update your Nest Thermostats software on a regular basis. 

Follow these steps:

  • Press the Ring on the Nest thermostat
  • Navigate to Settings
  • Select Update.

Nest Cycling On and Off Final Thoughts

Nest thermostats are typically reliable devices. There are things that could cause problems with them, but most of them are easy to repair.

If there are wiring issues, don’t try to handle live electrical wires yourself! Call a professional if you need help with any issues.

Check out these other articles to troubleshoot Nest thermostat issues: