Honeywell 'Cool On' (or snowflake) blinking — compressor protection delay

What this error means

A blinking 'Cool On' or snowflake icon means the thermostat is in its built-in compressor protection delay — typically about 5 minutes after a power interruption or cycle, protecting the AC compressor from short-cycling damage. It is not a fault. If it blinks far longer than 5 minutes, then you have a real problem (power, wiring, or system).

Symptoms

• 'Cool On' flashing on screen
• AC not starting immediately after being switched on
• Often after a power blip

Try this first (safe DIY steps)

1. Wait 5–10 minutes — if it goes solid and cooling starts, everything is working as designed
2. If still blinking after 10+ minutes: check batteries (if battery-powered), the system breaker, and the float switch
3. Power cycle the thermostat once

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

When to call a technician

Blinking that never resolves with power confirmed = 24V supply or wiring issue for a tech.