an optimizer for a single staged refrigeration system comprising a speed modulation device , controller , and supply air temperature sensor . the optimizer is intended for modulating the speed of the indoor fan and compressor in existing or new refrigeration systems in settings including but not limited to residential houses / buildings , residential heat pump systems , commercial heat pumps systems , water source heat pumps , and roof top units . the optimizer solves humidity and noise problems in existing systems , reduces peak demand , increases energy efficiency , reduces energy consumption rates , and minimizes compressor failure rates and o & amp ; m costs .