Thermostats
Error codes, troubleshooting, and maintenance information for thermostats.
Last updated: 2026-02-20
Troubleshooting
View all →Common Failure Modes
Smart thermostats can suffer from Wi-Fi chip failure or internal battery degradation. On older models, mechanical relays can stick, causing the AC or heat to run continuously.
Maintenance
View all →Replace batteries
Replace thermostat batteries annually before heating season, even if the low-battery indicator has not appeared. Dead batteries cause the thermostat to lose programming, Wi-Fi connection, and can leave your HVAC system without a control signal. Most thermostats use AA or AAA batteries.
Verify temperature accuracy
Place a reliable thermometer next to the thermostat for 15 minutes and compare readings. Most thermostats allow a calibration offset in the settings menu. A thermostat that reads 3 or more degrees off wastes energy by running the HVAC system longer or shorter than needed.
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