Thermostat reboots randomly several times a day without user input.

Safety warning: Turn off power to the indoor unit before tightening any low-voltage connections.

• 1. Tighten thermostat base connections:
  • Remove thermostat and tighten all terminal screws on the wall plate.
• 2. Inspect cable for damage:
  • Look for staples through the thermostat cable or crushed sections near the furnace.
• 3. Check transformer output:
  • A technician can measure voltage stability under load; replace transformer if voltage sags significantly.
• 4. Update or reset thermostat:
  • Apply firmware updates and perform a factory reset if recommended by Lennox.