Pressure testing

[walth]

Checked the static pressure and it is down to 30psi, what is the best way to pressure test the system? Does it have to be evacuated first or can I use argon to pressurize it to find the leak then evacuate and repair? 99 Dodge truck.

[GM Tech]

The best way to leak test is with a sniffer and UV dye- You can add a couple ounces of refrigerant to up the pressure to 80 psi or so-- the dye will tell you where it leaks- just not when it leaks- which is a good thing. Dodge trucks of your era are famous for evaporator leaks- so a sniffer in the vents, and UV dye evidence from the drain tube are paramount....