Sanyo's (Chatsworth, CA) "Eco Multi" air conditioning system uses both a standard compressor and a dual-cylinder power control compressor to respond to requirements in capacity by modulating the output of the compressor, realizing - by using an external save (bypass) valve - an eight-step compressor capacity control. Operating capacity of the indoor units can be stepped in 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, 87.5%, and 100% increments using a 16-bit microprocessor that ensures a more stable room temperature at a constant airflow rate.