Why is 'Cool On' or 'Heat On' flashing on my T6 Pro display?
The compressor protection feature is engaged, which requires a brief wait period after shutdown to prevent damage. You should wait 5 minutes before the system restarts. Once the safe interval has elapsed, the compressor will restart automatically. (Page 2)
From the official Honeywell T6 Pro Thermostat manual, page 2
Have a follow-up question?
Answers from the official manual.
Common questions