Great video. Those small , hard to find leaks can sometimes be present only during heat/thermal cycling.
Sometimes, running the engine, with hood closed will help with detection.
We have a cylinder of Nitrogen gas and the CPS Nitrogen leak detection kit that we connect and pressurize the system to 100 psi. Shutting off the manifold gauges, you can see the amount/rate of leak in the system. At the same time, we spray all joints, fitting, crimp hoses, etc using Safety Seal brand Leak Seeker solution (used for tire leak detection) and watch for the bubbles.
Keep in mind that in some cases, leak is from AC compressor front seal. To help locate those, we charge the AC system, run it a while. Then we put a womans shower cap over the front end of the compressor and let it sit for 30 minutes. Afterward, we use our electronic leak detector and see if refrigerant is trapped into the shower cap.
Depending on the leak location, UV dye might no always be effective depending on the location of the leak. Newer AC systems have such a small oil capacity that the UV dye might not be carried to the source of the leak effectively.
We do a lot of AC work in our shop. Have a contract to maintain a fleet of limos and a bus service that keeps us busy keeping the AC cold .
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