A2L Specific Service Procedures 2

Question 1

When performing a standing pressure test on an A2L system, what gas must be used?

Accepted Answer

Dry nitrogen — never pressurize with oxygen, air, or refrigerant for testing

Answer

Nitrogen is inert (non-flammable, non-reactive) and safe for pressure testing. Compressed air contains moisture and oxygen; oxygen with A2L refrigerant residue could create a dangerous mixture.

Question 2

What is the minimum evacuation (vacuum) level required before charging an A2L system?

Accepted Answer

Typically 500 microns (0.5 mm Hg) or below, held for a specified time, per manufacturer requirements

Answer

A deep vacuum (500 microns or lower) removes moisture and non-condensables from the system. Moisture is particularly problematic in A2L systems as it can create acids that degrade components.

Question 3

After brazing a repair on an A2L system, what tests must be performed before recharging?

Accepted Answer

Pressure test with nitrogen to verify the repair is leak-free, then evacuate to 500 microns to remove moisture, then leak test all connections before charging

Answer

Post-repair testing follows a sequence: verify the repair integrity (pressure test), prepare the system (evacuation), then verify all connections (leak test) before introducing flammable refrigerant.

Question 4

How should a technician handle an A2L system that has been contaminated with moisture?

Accepted Answer

Recover all refrigerant, replace the filter-drier, perform a triple evacuation with nitrogen breaks, and recharge with fresh refrigerant

Answer

Moisture contamination requires aggressive remediation: complete refrigerant recovery and disposal, new filter-drier, thorough evacuation (triple evacuation for severe contamination), and fresh charge.

Question 5

What is the correct method for checking an A2L system's superheat?

Accepted Answer

Same method as R-410A, but for A2L BLENDS, use the dew point (not boiling point) for the saturation temperature at suction pressure

Answer

Superheat measurement is the same concept, but for zeotropic A2L blends (like R-454B with temperature glide), the dew point temperature at suction pressure must be used, not the bubble point.

(A2L) A2L Low GWP Flammable Refrigerant Safety Certification Practice Test

(A2L) A2L Low GWP Flammable Refrigerant Safety Certification Practice Test

A2L Specific Service Procedures 2