Hi, It is a dye that is inserted through the suction line. The unit is allowed to run for a short time and then the system is scanned with a ultraviolet light that shows where the leak is. It will show as a bright yellow in color. Check around areas that are the weakest link in a system, joints, fittings, coils and so on. They are called a dye or leak detector dye kit. There is nothing that can be inserted into a system to repair a leak just to locate it for repairs only.
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