Why is 'Cool On' or 'Heat On' flashing on my thermostat display?

The flashing 'Cool On' or 'Heat On' message indicates that the compressor protection feature is engaged. This prevents damage to the compressor by forcing it to wait a few minutes before restarting after shutdown. Wait approximately 5 minutes for the safe restart time to elapse, at which point the message will stop flashing and the compressor will turn on.