Carrier 42NQV025H Service Manual

Contents

– 14 –Gauge manifold[ Cylinder with siphon ] [ Cylinder without siphon ]OUTDOOR unitGauge manifoldOUTDOOR unitRefrigerantcylinderElectronicbalanceRefrigerantcylinderElectronicbalanceSiphon1. Be sure to make setting so that liquid can be charged.2. When using a cylinder equipped with a siphon, liquid can be charged without turning it upside down.It is necessary for charging refrigerant under condition of liquid because R410A is mixed type of refrigerant.Accordingly, when charging refrigerant from the refrigerant cylinder to the equipment, charge it turning thecylinder upside down if cylinder is not equipped with siphon.R410A refrigerant is HFC mixed refrigerant.Therefore, if it is charged with gas, the composi-tion of the charged refrigerant changes and thecharacteristics of the equipment varies.3-5. Brazing of Pipes3-5-1. Materials for Brazing1. Silver brazing fillerSilver brazing filler is an alloy mainly composedof silver and copper. It is used to join iron, copperor copper alloy, and is relatively expensive thoughit excels in solderability.2. Phosphor bronze brazing fillerPhosphor bronze brazing filler is generally usedto join copper or copper alloy.3. Low temperature brazing fillerLow temperature brazing filler is generally calledsolder, and is an alloy of tin and lead. Since it isweak in adhesive strength, do not use it forrefrigerant pipes.1. Phosphor bronze brazing filler tends to reactwith sulfur and produce a fragile compoundwater solution, which may cause a gasleakage. Therefore, use any other type ofbrazing filler at a hot spring resort, etc., andcoat the surface with a paint.2. When performing brazing again at time ofservicing, use the same type of brazing filler.3-5-2. Flux1. Reason why flux is necessary• By removing the oxide film and any foreignmatter on the metal surface, it assists the flowof brazing filler.• In the brazing process, it prevents the metalsurface from being oxidized.• By reducing the brazing filler’s surface tension,the brazing filler adheres better to the treatedmetal.Fig. 3-4-2FILE NO. SVM-07013