A universal controller for control of air handling and HVAC equipment. The base controller includes a fixed task portion as well as a modular portion for expansion of control features with modules. The fixed task portion is suitable for enclosure or cabinet control. The modular portion enables expansion from basic cabinet control to more complex control schemes. In one embodiment, the base controller is provided in a kit including appurtenances such as variable speed drives that enable proportional-type control of a residential air conditioning system. In another embodiment, a plurality of modules are ganged together in a rotating master/slave arrangement to distribute wear on the respective controlled air conditioning equipment.