“Variable speed” is a term that is relatively new to HVAC. Older air conditioning and heating systems did not have the ability to efficiently control fan speed in quite the same way as today’s variable speed heat pumps do. With a standard system, a blower fan runs at a single speed, and continues to blow air until the temperature in the home has reached the setting on the thermostat. But new technology has allowed for the creation of variable speed heat pumps for the ultimate in efficiency and performance.