Why is 'Cool On' or 'Heat On' flashing on my thermostat display?
The flashing 'Cool On' or 'Heat On' message means the built-in compressor protection feature is engaged. You must wait 5 minutes for the system to restart safely to prevent damage to the compressor. Once the safe wait time has elapsed, the message stops flashing and the compressor turns on. (Page 19, 15)
From the official Honeywell Focuspro Th6110d manual, page 15
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