In most instances, leaking evaporator coils are not repairable. This is because the metals are corroding and breaking down, and the holes are numerous microscopic pinholes packed into dense layers of aluminum fins and copper tubing. In some instances there is a specific leak source that can be repaired. Also, depending on how old a component is, the cost of a repair may approach the replacement cost of a new component. A technician can determine whether or not a leak is repairable.