Honeywell Home error codes, explained
T-series and classic Honeywell Home thermostats. Codes below: Display messages ('Cool On' blinking, 'Wait'…). Each guide covers what the code means, what you can safely try yourself, when to stop and call a technician, and what the repair typically costs.
Honeywell 'Cool On' (or snowflake) blinking — compressor protection delay
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).
Honeywell 'Wait' message
'Wait' on Honeywell Home thermostats is the same compressor-protection hold — the thermostat pauses the system briefly (up to ~5 minutes) to protect the compressor, usually after a settings change or power interruption.
Honeywell thermostat screen blank
Dead display = no power reaching the thermostat: dead batteries (many Honeywell models are battery-powered), a tripped breaker or furnace switch, a tripped float switch, or a blown low-voltage fuse.