First, confirm the thermostat is calling for heat correctly. Go to Menu > System Mode. Set it to Heat and Done. Ensure the set temperature is higher than the current room temperature. If it still doesn't run, follow this sequence.
- Circuit breaker for the HVAC system? Check and reset.
- Furnace power switch? Must be ON.
- Furnace door or panel? Close it securely.
- C-wire connection? Verify at both the thermostat and furnace control board.
- Wait 5 minutes for the system to respond.
If that didn't work: The problem is likely at the W terminal (heat).
- Check your wiring photo from the old thermostat. Was there a wire in W or W1?
- At your new T9 wall plate, ensure that wire is firmly inserted into the W-terminal.
- At the furnace control board, verify the other end of that same wire is connected to the W-terminal.
Heads up: For heat pump systems, a wire in the W terminal on the UWP can cause the auxiliary heat to run during a cooling call. Make sure your system type is configured correctly in the thermostat settings.