Fixing refrigerant leaks is a tedious but important task. The following tips can help prevent leaks and speed their repair:

• Use rubber-gasketed brass caps for all service port connections and keep them wrench-tight (rather than just hand-tight). Have plenty of spares on hand—like the valve caps on your car tires, they have a way of wandering off. Replace these gaskets (or the complete caps) periodically, because they can become dry and cracked.

• Enforce a standard of cleanliness for all refrigerant lines. Keep the copper pipes wiped down with a clean rag. Refrigerant leaks also leak oil, and it is easier to find oil on clean pipes.

• Look for leaks first on flanged and screw fittings, rather than on soldered joints.

• Minimize the number of times that refrigerant gauges must be connected to the service ports—each time this happens, it bleeds a bit of refrigerant from the system.

• Repair a leaking coil only once and mark it with paint or chalk. The next time it leaks, replace the coil completely.

Repairing refrigerant leaks requires several steps, including refrigerant recovery, nitrogen charging, inspection with a leak detector, brazing or otherwise fixing the leak, vacuum drying, and recharging. Fixing a refrigerant leak can cost from US$250 to as much as $1,000 if components such as the evaporator coil must be replaced.