ecobee screen blank / no power

What this error means

ecobee thermostats require a C (common) wire or the included Power Extender Kit — a blank screen almost always means the 24V supply is interrupted: tripped float switch, blown control-board fuse, breaker, or a loose C wire.

Symptoms

• Black/blank screen
• Thermostat rebooting repeatedly
• Appeared after HVAC service or a power event

Try this first (safe DIY steps)

1. Check the HVAC breaker and the furnace/air-handler service switch
2. Check the condensate float switch (full drain pan cuts 24V on many systems)
3. Pull the ecobee off its backplate and reseat it firmly
4. If installed with the Power Extender Kit, verify its connections at the control board (power off first)

Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.

When to call a technician

If breakers, float switch, and reseating don't restore power — likely a blown low-voltage fuse or transformer; a quick diagnostic for a tech.