Uniweld, P4KD9S, UNI-4300 Aluminum Solder [10 ft. coil] with a 2 oz. Flux Bottle & Metal Tip Flux Applicator
Uniweld's UNI-4300 aluminum soft solder kit with metal tip flux applicator is a great solution for the service technician who is frequently confronted with the task of repairing or joining aluminum to aluminum and aluminum to copper or brass. A common repair problem occurs when an air conditioning system's evaporator coil develops a small pinhole leak. UNI-4300 is an excellent product for this repair application due to its low melting point of 500 °F [260 °C] and 20,000 PSI tensile strength.
For best results, prepare the tubing by cleaning the surface and removing any oil, grease and oxides. To remove the oil and grease, use a chemical solvent. The oxides should be removed using only a stainless steel wire brush or emery cloth. TUBING SURFACES MUST BE CLEAN.
When making a repair on an evaporator coil, it will be necessary to preheat the tubing prior to applying the flux. A common mistake when making this type of repair is to apply the flux and then begin heating the tubing. The evaporator coil disperses the heat and the tubing never reaches the melting temperature of the alloy. The flux overheats and burns, then becomes an inhibitor that doesn't allow the alloy to bond properly to the base metal.
Preheat the evaporator tubing and then apply the flux using the metal tip flux applicator. Continue applying heat until the flux starts to bubble and then apply the UNI-4300 solder into the area being repaired.