These products are used in systems that are leaking refrigerant. The manufactures of these products say they do no harm to the system, but air conditioning systems consist of metering devices that may be fixed piston type or expansion valve type. Pistons have metering bore holes. And they have screens in the fitting that catches debris that may have been missed by the filter dryer. Expansion valves have screens, needle pins, seat fittings. And some expansions valves have ball valves that are used in replacing the needle. Electronic expansion valves operate with stepper motors allowing the refrigerant to move through the valves. Capillary tubes control refrigerant through small and accurate size tubing and are usually equipped with fine filter dryers which remove moisture and dirt, keeping the tubes from getting clogged. So what will this stop leak products do to these valves and filter dryers? Most of the air conditioning equipment made today has Emerson Copeland Compressors, the manufactures of these compressors do not want this product in the refrigerant system. This product is too new to know what the long term effect will be. In my opinion it would be better to repair the leak if it can be done, or replace the part that is leaking.