System Components
System Components tests your knowledge of how installed parts work together: line sets, metering devices, coils, service valves, filter driers, condensate removal, and evacuation. The exam focuses on installation sequence and the failure modes created by shortcuts.
Line sets and metering
Size and route line sets per the manufacturer and local code. Insulate the suction line fully, support it, and avoid sharp bends. Use a bi-flow filter drier rated for the system. When brazing, purge with dry nitrogen to prevent internal oxidation; protect service valves and TXV bodies with a heat sink or wet rag. Mount a TXV bulb on the suction line, insulated and oriented per instructions.
Evacuation and dehydration
Leak-test with dry nitrogen, then evacuate to 500 microns or lower and hold. A rising vacuum after isolation indicates a leak or moisture; moisture requires deeper evacuation or a new drier. Open service valves fully after the hold. Condensate lines need a trap, continuous slope, and a secondary pan with float switch where required.
Worked example
A 3-ton split system is pulled to 300 microns and isolated. In 10 minutes it rises to 1,500 microns. That is too fast for residual moisture alone and suggests a leak. Pressurize with nitrogen, locate and repair the leak, replace the filter drier if it was exposed, then evacuate again.
Traps
- Brazing without nitrogen purge.
- Skipping the vacuum hold.
- Missing or dry condensate trap.
- TXV bulb loose, uninsulated, or on the wrong line.