What should I do if the display shows 'Cool On' or 'Heat On' flashing?
The flashing 'Cool On' or 'Heat On' message indicates that the compressor protection feature is engaged. This prevents damage to your air conditioning or heat pump system by forcing the compressor to wait a few minutes before restarting. Wait 5 minutes for the system to safely restart without damage to the compressor.
From the official Honeywell 6000 Series Programmable Thermostat manual, page 15
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