Learn what causes these errors
The Nest thermostat is designed to work in most cases without a common wire. Instead of using a common wire to keep your thermostat charged, your Nest thermostat can use the Y1 (air conditioner) wire to power itself.
If your air conditioner stops sending power to your thermostat, your thermostat can let you know with one of these errors. There are a number of reasons why your air conditioner might stop sending power to your thermostat. Below we list some possible reasons, but it’s important to contact a professional to diagnose your system and determine what the root cause of the error is.
One possible reason is that your system needs maintenance. If your system breaks down, it will likely stop sending power to your thermostat. An HVAC professional can help determine if your system needs repair.
Another possible reason is that you live in an area that experiences very cold temperatures in winter. Your air conditioner may come equipped with a safety device that will stop it from turning on in extremely cold weather to prevent damage. These safety devices, sometimes called low pressure switches (LPS) or safety cut-out switches, can sometimes prevent your air conditioner from providing your Nest thermostat with power in extremely low temperature conditions.
If you see one of these errors (E10, E30, E66, E80, E116, E160, E196 or M13), you can use the quick fix below to help get the heat back on. Then, when it's convenient, call an HVAC professional such as a Nest Pro to come take a look at your system and install a common wire.
Troubleshoot to get heating back on
|1. Turn off the power to your heating and cooling
system at the main breaker for your home.
|2. Grip the ring of your thermostat and pull it gently
towards you away from the wall. Your thermostat
should pop right off the base.
3. Take a picture of your wiring in case you need it later.
4. Remove any Y wires (Y, Y1, Y2) from the Nest base.
Tip: You can remove a wire by pressing down on the
5. Wrap the exposed end of each wire you removed
6. Put the display back on the base. Make sure the
7. Turn your breaker back on and see if your Nest
If your Nest thermostat powers on without an error,
Note: You may see the message "The wiring to your
Important: You won't be able to use your AC until you reconnect
8. If your Nest thermostat doesn't power on, remove the display
Install a common wire to prevent future problems
With your HVAC system configuration, it is recommended that you have a professional install a C or common wire to prevent power issues in the future.
Tip: You may already have an unused wire behind your thermostat that can be used as a C wire. An HVAC professional such as a Nest Pro should be able to repurpose this wire into a new C wire without needing to run a new wire to your thermostat.
Contact an HVAC professional or a Nest Pro to learn more about having a common wire installed. After a common wire installed, your professional installer will be able to reattach the Y1 wire to your Nest thermostat. Once the Y1 wire is reconnected, you can continue using both your heating and cooling systems.
Note: Nest Pros are a network of independent companies or contractors and are not employed by Nest.