The Tracerline LeakFinder Universal A/C Dye, No. LF1001, is an ultraviolet fluorescent universal dye designed to provide precise leak detection for all automotive air conditioning systems containing R-134a, R-1234yf or other widely used refrigerants. This specialty dye can safely be added to the system without affecting the system's lubricant properties or changing how the equipment works. The LF1001 helps find small, problematic leaks that would otherwise be almost impossible to detect, the company says.