A forced air cooling unit for a light source formed of an array of high intensity light emitting diodes (LEDs). A housing includes side walls with a pair of grooves on the inside of the walls. A heat sink includes side extensions which are slidably received in the grooves. The LED array is mounted in thermal contact with the heat sink so as to protrude from the top of the housing. The housing side walls include a second pair of inside grooves below the first pair. The second pair of grooves slidably receive a cooling fan base plate. An internal air flow chamber thus defined by the housing side walls, the base plate and the heat sink. A cooling fan, mounted at one end of the base plate, draws cooling air into internal chamber. The air flows by the heat sink, carrying with it heat generated by the LEDs, to the other opposite end of the base plate, where it exits the internal chamber through openings in the base plate. The cooling units are self-contained and modular and can be mounted side-by-side or end-to-end to accommodate a variety of LED array sizes and configurations.