Why is this worth checking with a leak detector?

Leak detection · EPA 608 Type II. The correct answer, and the reasoning behind it.

Signs of leaks in high-pressure systems and leak testing before charging.

The question

While inspecting a hermetic R-22 system, a technician finds an oily film around a brazed joint on the suction line. Why is this worth checking with a leak detector?

• AOil residue at a joint is a common sign of a refrigerant leakCorrect answer
• BIt shows the compressor has too much oil
• CIt means the joint was overheated when it was brazed at the factory
• DIt shows moisture has entered the system

Why “Oil residue at a joint is a common sign of a refrigerant leak” is correct

Refrigerant carries compressor oil around the circuit, so oil escapes with refrigerant at a leak and leaves a trace. EPA names traces of oil as a sign of leakage in hermetic systems.

Source: EPA: Test Topics

Why the other answers are wrong

• It shows the compressor has too much oil — Oil outside a joint does not measure the compressor's oil level.
• It means the joint was overheated when it was brazed at the factory — Overheating while brazing does not by itself leave an oily film.
• It shows moisture has entered the system — Moisture inside the system does not show up as oil on the outside of a joint.

Practice more of this

More EPA 608 Type II practice questions, or see every EPA 608 practice test.