What does the 'Cool On' or 'Heat On' flashing message mean?

When 'Cool On' or 'Heat On' flashes on the display, the compressor protection feature is engaged. This is a safety mechanism that prevents damage to the compressor. You should wait 5 minutes for the system to restart safely before the compressor will resume operation. Do not attempt to force the system to restart during this protection period.

From the official Honeywell T6 Pro TH6210U2001 Thermostat manual, page 13

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