A blinking or flashing display on a thermostat indicating “cool on” typically signifies a delay. This delay is often programmed into the system to protect the air conditioning compressor from damage. Rapidly cycling the compressor on and off can significantly shorten its lifespan; the delay ensures a period of rest between cycles. The manifestation can be seen when the user adjusts the temperature significantly lower, calling for cooling, or after a power interruption when the system is attempting to restart. The visual cue alerts the user that the system is responding but is intentionally paused.
This protective feature is essential for the longevity and efficient operation of central air conditioning units. Compressors are complex and expensive components, and repeated, abrupt starts place considerable stress on their mechanical and electrical systems. By implementing a brief delay, manufacturers mitigate the risk of premature failure, resulting in reduced maintenance costs and extending the overall service life of the air conditioning system. The implementation of such delays has become a standard practice in modern HVAC systems, reflecting an emphasis on durability and energy conservation.