What does it mean when 'Cool On' or 'Heat On' is flashing on the display?
A flashing 'Cool On' or 'Heat On' message indicates the compressor protection feature is active and the compressor is waiting before restarting. This delay is controlled by Setup Function 15 and is designed to prevent equipment damage from rapid compressor cycling. (Page 8)
From the official Honeywell Pro Th3210d manual, page 8
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