Common Competencies: Tools and Equipment, Measurement, Materials Handling, Documentation
Scope
This domain tests whether you select the right tool, use it without damaging the equipment, measure to the tolerance the manual specifies, handle tubing, refrigerant and electrical materials correctly, and record what you did so the next technician can follow.
Tools
A manifold gauge set must be rated for the system pressure (R-410A needs 800 psi class gauges, not R-22-only manifolds). Typical kit: two-stage vacuum pump with micron gauge, recovery machine, flaring block with eccentric cone, swaging and deburring tools, tube bender, torque wrench, dry-nitrogen regulator, electronic leak detector, true-RMS clamp meter, insulation tester, contact thermometer.
Measurement
- Manifold gauges read psig; convert to saturation temperature with the refrigerant's pressure-temperature chart, not by guesswork.
- Copper tube outside diameter: 6.35 mm = 1/4 in, 9.52 mm = 3/8 in, 12.70 mm = 1/2 in, 15.88 mm = 5/8 in.
- Flare nuts are torqued to the manual's table (about 14–18 N·m for 1/4 in, 34–42 N·m for 3/8 in), never "tight by feel".
Materials handling
Keep tube ends capped until the moment of assembly; anneal hard copper before bending; store brazing rods dry; keep nitrogen and refrigerant cylinders upright, secured and fitted with the correct regulator; never roll or drop a cylinder.
Documentation
Job order, service report, refrigerant usage log, parts replacement record and tool inventory. Record serial numbers, pressures, temperatures, amps, charge added and parts fitted.
Worked example
A caliper reads 9.50 mm on a suction line. The 3/8 in nominal size is 9.52 mm, so within 0.02 mm this is a 3/8 in tube: select a 3/8 in flare nut, confirm the tube is annealed and cut square, deburr, slide the nut on before flaring, then torque to the manual's 3/8 in figure. Had you flared first, the nut would not fit and the joint would be scrapped.
Traps
Mixing millimetre and inch sizes; using an adjustable wrench on flare nuts; over-torquing until the cone splits; using a pipe wrench on gauge bodies; forgetting to zero or hold the reading on the clamp meter.