A method for cleaning the interior of a heat exchanger includes connecting the heat exchanger (25a-e) to a fluid supply (26) and fluid delivery system (24). Fluid flow is provided from the fluid supply (26) through the interior of the heat exchanger (25a) in a first direction. The fluid flow is pulsed a predetermined number of times to change the pressure within the heat exchanger. The fluid flow is then pulsed a plurality of times through the heat exchanger in a second direction.