Did you know that your air conditioner still holds cold air after it stops running? After your air compressor shuts off, cooling capacity remains because the cooling coil is still cold. Cool control devices take advantage of this by running the fan a few minutes longer to take advantage of the cold coil by blowing air across it to continue to cool your house.
For most systems, the fan will run for up to 5 minutes after your air compressor turns off. On extremely hot days the fan may run for longer periods of time with the air compressor cycling on and off. Even though the fan uses electricity to run, running your entire air conditioning system uses more. The device runs your fan more while the coil is still cool to save money from not needing the whole system turned on.
By using all of the cooling capacity from your air conditioner you can save up to 10% on your cooling bill. The cool control device saves energy every time your AC unit runs.