Question: My technician told me he could not locate the leak in my system, so he topped-off the refrigerant in my car, but did not perform any leak repair. Now it seems to be low on refrigerant again -- I know the leak is still there. What can I do?

Answer: Leaks can be identified most, but not all, of the time. Your technician may have difficulty locating very small leaks in your a/c system, even if he is very careful and uses the most sophisticated equipment available. Keep in mind that even when pinhole leaks cause slow emissions over long periods of time, your system may seem to lose its cooling capacity suddenly. This is because most motor vehicle a/c systems have controls that shut off a system when the system pressure drops below a certain point. In order to maximize the chances that your technician can locate the leak, make sure he uses an electronic leak detector certified under the Society of Automotive Engineers (SAE) J1627 standard. Note that the system does not need to contain a full charge of refrigerant to locate the leak -- a few ounces of refrigerant (about 10% of the normal charge) is sufficient to perform the leak check. Some technicians may also use a trace dye and a black light to help find persistent leaks.