Abstract: The present invention provides a device that uses an ultraviolet LED to locate fluorescent materials. In particular, the present invention is directed to a device that is used to detect leaks, cracks or fissures in a contained system, such as, for example, an air conditioning system for a vehicle. The device has a main body, an ultraviolet LED mounted to the main body so that ultraviolet light from the LED is directed away from the device, and a power source linked to the ultraviolet LED to provide power to the LED. The ultraviolet LED can be an UVA LED. Moreover, the wavelength of the ultraviolet light produced by the LED is about 315 nm to about 400 nm. The method of the invention for locating fluid leaks can comprise, for example, introducing an ultraviolet dye into a fluid in a contained system, such as, for example, an air conditioning system of a vehicle, and illuminating an area of the system to be checked for fluid leaks with an ultraviolet LED light source.