An improved patient temperature exchange system and method is disclosed for use with one or more interconnectable patient contact pads. In one embodiment, the system includes a circulating pump (20) for drawing fluid through the interconnected pad(s) (1) under negative pressure, and for pumping the fluid through one of more heat exchange devices (66) into a circulating reservoir (30). Also included in the system is a controller (130) specially configured for controlling the one or more heat exchange devices. The controller is further configured to employ one or more algorithms for adding and removing heat in a predetermined manner. One algorithm may include first and second control terms which provide for a theoretical heat transfer rate as well as instructions for changing temperature in an expedient manner while reducing isolations and overshoots. The system may be further configured with at least one alternate mode for affecting water temperature when one or more water temperatures are outside a predetermined range.
