EF Products R134a UV Dye, 12.3 oz. (334)

I never did find a UV marked leak, but I didn't look all that hard.

Good for finding leaks in your vehicle AC. You also need a UV light. Found my leak in my Schrader valve.

The dye performed its function, I was able to diagnose an AC leak.

I use this for all of the systems that I work on. With a black light it is relatively easy to find A/C system leaks. This is the only R-134a refrigerant I could find that did not have the leak sealer which you do not want if you plan on owning your car for more than a week after dispensing into your A/C system.

Our company mechanic was able to visualize leaks on our company car with this product and fix the problems. He said it was easy to use and did not require opening the AC system to dump in dye.