Nest Thermostat Learning - heat shuts off/kicks back on

[PBriggs16]

Installed my thermostat with no C wire.  My unit is a best only gas furnace with forced air.  The thermostat is technically working, though it frequently behaves oddly.  In the mornings when needing to go from say 63 to 68, it will run for 60 seconds or so then shut off, then run again and shut off.  Often times when it does get to temp, the unit will click constantly like it’s in between wanting to turn it on or not.  No issues with the battery draining on the thermostat.  The red wire is hot and seems to power it fine.  I have the ability to use a C wire, but would that solve any of these strange issues?

[zoeuvre]

Hi PBriggs16, 

Uh-oh! If you have installed your Nest thermostat without a C wire and are experiencing odd behavior, such as short cycling and constant clicking of the unit, it is possible that the lack of a C wire is causing power-related issues. The C wire provides a continuous power supply to the thermostat, which helps ensure stable operation and prevents issues like short cycling. Here are a few steps you can take to address the problem:

1. The most reliable solution is to install a C wire (also known as a common wire) to provide a dedicated power source to the thermostat. This can typically be done by connecting the C wire to the C terminal on your furnace control board and the C terminal on the Nest thermostat base. This will ensure a continuous power supply to the thermostat and can help resolve the odd behavior you are experiencing.
2. Double-check all wiring connections to ensure they are properly seated and secure. Loose or incorrect wiring can result in erratic behavior. Verify that all wires are connected to their respective terminals correctly, following the Nest Thermostat's installation guide or consulting a professional if needed.
3. Try performing a reset of the Nest thermostat to clear any temporary glitches. To do this, go to the thermostat settings and select "Reset" or "All Settings." Follow the on-screen prompts to complete the reset process. Afterward, reconfigure the thermostat settings and test its operation.

Installing a C wire is generally the best solution to ensure stable and reliable operation of your Nest Thermostat, especially if you are experiencing odd behavior like short cycling and constant clicking. It provides a consistent power supply and can help resolve power-related issues.

Let us know if that helps.

Best,

Zoe