What should I do if the display shows 'Cool On' or 'Heat On' flashing?
The compressor protection feature is engaged, which prevents damage by waiting before restarting the compressor. Wait 5 minutes for the system to restart safely without damaging the compressor. Once the safe wait time has elapsed, the flashing message will stop and the compressor will turn on.
From the official Honeywell TH6110D Programmable Digital Thermostat manual, page 15
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