Why is my cooling/heating running constantly?

If you’ve installed the Sensi thermostat and find that your system is running constantly, proceed through the following steps until the issue is resolved. 

Test Thermostat Operation

1. Make sure the thermostat is set to Fan Auto. Set your thermostat Mode to Off and Fan to Auto. When the thermostat is set to Fan On it may sound like the heating or cooling is running even when it isn’t.
   • Make sure that the Circulating Fan feature is not active.
   • Make sure that any humidity control features are not active.
     • Learn more about humidification control here
     • Learn more about dehumidification control here
2. If your system still runs after 1-2 minutes, remove the thermostat.
   • Remove the thermostat face plate from the sub-base. 
   • Check each wire connection on the wall plate, and make sure they’re secure in the terminal blocks. You want to tug on each wire to ensure they’re secure.
   • Make sure the wires are not touching each other. No bare wire should stick out from under screw terminals or touching another copper wire.
   • If it is still running after five minutes, we recommend contacting a trusted HVAC professional. There may be a short in the wiring to the equipment.
3. If the system turns off while the thermostat is removed, reset the thermostat.
4. Now test your thermostat.
   • Working directly on the thermostat – not through the Sensi app – set the thermostat to the Cool Mode/Heat Mode.
   • Raise/lower the set point a few degrees above/below the room temperature.
   • Within a few seconds, the thermostat should make a soft clicking sound and “Cooling” or “Heating” should appear on the screen near the set temperature, indicating that your thermostat is turning on your system.
   • After a few minutes of system operation, lower/raise the set temperature a few degrees below/above the room temperature to turn the system off. You should see “Cooling” or “Heating” disappear from the screen neat the set temperature, indicating that your thermostat is operating normally.

Verify Wiring and Configuration

If your system is still not turning off, confirm that you labeled and installed your wires properly. 

Does your old thermostat have two sets of terminal labels? Learn more here and be sure you’re entering the correct terminals that correspond to your system type (Conventional or Heat Pump). 

For wiring terminal designation information, refer to the wiring diagrams on your Sensi model’s Install Guide.

Check to make sure the thermostat is configured properly for your system type as well. Learn more about how to configure your thermostat here.

Testing Continuity

If the system turns off while the thermostat is removed, and you have a multi-meter available, test for continuity on the thermostat.
Note: You can only test continuity on the Sensi Smart Thermostat.

1. Set the multi-meter to Ohms (Ω).
2. Make sure the face plate is set for Fan AUTO and Mode OFF.
3. Now test for continuity on the pins on the back of the thermostat face plate from RC or RH to the terminals corresponding to the device running (G – fan, W/E – furnace, Y – compressor).
   • NOTE: DO NOT TEST CONTINUITY ON THE THERMOSTAT SUB-BASE TERMINALS OR THE MULTIMETER WILL BE DAMAGED.
4. For your fan or compressor running constantly, make sure to test between RC and Y and RC and G. Put one test probe on the pin labeled RC and the other test probe on the pin labeled Y. 
5. For your heating running constantly, make sure to test between RH and W/E. Put one test probe on the pin labelled RH and the other test probe on the pin labelled W/E.
   • If continuity is detected when set for Fan AUTO and Mode OFF, replace the thermostat.
   • If continuity is not detected, the thermostat is operating properly and not calling for the corresponding system component.
   • If continuity is not detected, and replacing the thermostat face plate makes the system run continuously again, your system may have a sensitive equipment circuit that is reacting to the power sharing feature in the thermostat. Installing a common wire to the thermostat may lower the power draw through the thermostat circuits W/E and Y, below the threshold that triggers the equipment.
     • For options for adding a common wire, please check out our c-wire videos.