The power center of an iQ Drive® system is its patent-pending controller. Installed inside the home, the controller “talks” to the outdoor unit, assessing 
the cooling load of the space and using the information to compute and communicate the ideal speeds to the inverter and indoor fan.
The inverter and controller also get continuous feedback from the compressor in case further adjustments are necessary. This communication occurs multiple times every second for nearly constant interaction.
If paired with an air handler, the controller also calibrates the indoor blower on a periodic basis, performing a load calculation on the duct system and measuring resistance to airflow in order to learn the duct characteristics of the home and perform at optimum efficiency. When matched with a high-efficiency furnace, the controller communicates with the blower, and indirectly with the furnace controls, to achieve the same flexible result.
The controller also has diagnostic capabilities, alerting the homeowner when a service call is needed and providing the service technician with information to help him or her quickly assess the problem.
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