Nest e160 error

[Gwands]

Hello, I switched my Nest E thermostat from cool to heat this morning for the first time in about a month or so.  I then started receiving the E160 error about every 8-10 minutes.  My furnace is running and it is producing heat.  When I looked up the E160 error it says it is an AC error, so I’m not sure what is going on.  Please help.

[Patrick_Caezza]

@Gwands 

You'll get the E160 error code if your air conditioner has tripped a safety cut-out switch that prevents your air conditioner from turning on in very cold weather, or your system might need maintenance.

Google Nest thermostats are 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 notify you with one of these errors. There are a number of reasons your air conditioner might stop sending power to your thermostat. 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'll 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 might come equipped with a safety device that'll stop it from turning on in extremely cold weather to prevent damage. These safety devices, sometimes called low-pressure switches (LPS) or safety cutout switches, can sometimes prevent your air conditioner from providing your Nest thermostat with power in extremely low temperature conditions.

Sometimes you can easily fix this problem by installing a C wire if one isn't already installed

[Gwands]

Hello, thank you.  Unfortunately this issue is only happening when I have it run my furnace, not the A/C Unit.  As soon as I switched it over to heat, it started happening.  The furnace is still working and producing heat, I just keep getting the error.  Could it be that the Nest needs to be replaced?  I bought it back in September of 2017.  
Thank you!

[aperezdeleon]

Hi Gwands,

Thanks for posting in our community and Patrick_Caezza for the rundown.

Getting sudden E160 error codes in your Nest thermostat can be puzzling, especially since the A/C isn’t being used. Don’t worry, let's get to the bottom of this and make sure your Nest thermostat is up and running the way it was before.

The E160 error code is specifically trying to tell you that the Y1 wire in your Nest thermostat is not receiving enough power. This wire comes directly from your cooling equipment (in this case, your A/C). Your thermostat may display this error code for a variety of reasons.

A common reason the E160 error code might appear, mentioned by Patrick_Caezza, is that your A/C unit has stopped sending power to your thermostat. Even though the A/C unit is not being used, the Y1 wire will still aid in ensuring enough power is provided for the thermostat to work as expected. Have you used your A/C unit after changing the mode to heating? Was your A/C able to turn on?

In the meantime, checking if your wires are sitting properly on the Nest Thermostat’s base is a good first step to get rid of the sudden E160 error codes.

Let me know what you find out.

Regards,
Angel.