No Heat or Cooling

Symptoms

• Thermostat display is on and set to heat or cool, but system does not activate
• No airflow from vents after the set temperature is reached
• The word "Heating" or "Cooling" appears on screen but nothing happens

Likely Causes

1. System is in a built-in delay cycle (compressor protection)
2. Heating or cooling function is disabled in the settings
3. Wiring terminal loose or incorrectly labelled during installation
4. The C-wire adapter is not seated correctly, causing intermittent power
5. The HVAC unit itself has tripped a safety switch or blown a fuse

Step-by-step Fix

1. Wait 5 minutes after changing the set temperature. The T1 applies a 3-minute minimum delay before activating heating or cooling to protect the compressor. If the system starts after waiting, no action is required.
2. On the thermostat, go to Settings > System Mode and confirm that Heat, Cool, or Auto is selected — not Off.
3. Check that the set temperature is at least 2 °C above (for heat) or below (for cool) the current room temperature. A smaller differential may not trigger the system.
4. Switch off power at the breaker. Remove the T1 from its wall plate and inspect all wiring connections. Re-seat any wires that appear loose or partially inserted.
5. Locate the air handler or furnace unit and check for a tripped safety switch, blown fuse, or error light on the unit itself. Refer to your HVAC unit's manual if a fault is indicated.
6. Restore power and retest.