Review on 🌡️ FJC Inc. 6025 Quick Coupler Manifold Gauge Set Conversion Kit: Optimize Refrigeration System Performance by Matthew Evans

The quality of these adapters looks very good. I had no problem screwing existing R12 hose fittings to these adapters and connecting and testing the R134a system. I haven't had any leaks and basically these adapters have allowed me to use my old A/C manifold sensor with R12 hoses/fittings on R134a vehicles. These adapters saved me from buying a new set of R134a hoses and Acme R12-R134a adapters (which is a lot more expensive in this case). These adapters have another function. Once you disconnect the adapter from the AC system, the pressure that has built up in your pressure gauge won't come out straight. They basically block any back pressure, allowing you to safely vent any remaining pressure in your gauge using the manifold valve knobs. For example, I connect the middle yellow hose (refill hose) and let it dangle freely. When I'm done checking the system, I disconnect the red and blue quick disconnects from my car (you don't see freon or hiss after disconnecting). Then I move my pressure gauge out somewhere and slowly turn each red and blue hose manifold knob while pointing the yellow hose in a safe direction until the pressure is safely relieved. This is the first and only set of R12-r134a I will ever need.