EPA 609 Practice Test 2 Flashcards

Under EPA Section 609, technicians must be certified through which type of program?

Answer: An EPA-approved 609 certification program offered by approved organizations

EPA Section 609 requires that technicians servicing MVAC systems be trained and certified under an EPA-approved program. Multiple organizations offer EPA-approved 609 training and certification, including automotive trade associations and training providers. ASE certification alone does not satisfy Section 609 requirements, though many technicians hold both.

What is the correct procedure when an automotive A/C system is suspected of being contaminated with the wrong refrigerant?

Answer: Use a refrigerant identifier to confirm contamination before recovery

Before recovering any refrigerant from a suspected contaminated MVAC system, a refrigerant identifier must be used to determine the system's actual contents. This prevents cross-contamination of recovery cylinders, which could render entire cylinders of refrigerant unusable. Contaminated refrigerant must be recovered separately and handled according to the contamination type identified.

What does R-1234yf have in common with R-134a that makes it suitable as a replacement in automotive A/C systems?

Answer: Similar thermodynamic performance at automotive A/C temperatures, though slightly lower GWP

R-1234yf has thermodynamic properties similar to R-134a at typical automotive A/C operating temperatures, delivering comparable cooling performance. This makes the transition feasible for new vehicle designs. However, R-1234yf has a GWP of just 4 vs. R-134a's 1,430. Key difference: R-1234yf is classified A2L (mildly flammable), unlike R-134a (A1), requiring updated service procedures and dedicated service equipment.

How does the orifice tube differ from a TXV in automotive A/C systems?

Answer: The orifice tube is a fixed restriction metering device; the TXV modulates flow based on superheat

An orifice tube is a fixed restriction device that meters refrigerant flow at a constant rate regardless of system conditions. A TXV (thermostatic expansion valve) actively modulates refrigerant flow in response to evaporator superheat through a temperature-sensing bulb. Orifice tube systems use an accumulator on the suction side; TXV systems use a receiver-drier on the liquid side.

What symptom indicates that an MVAC system has been overcharged with refrigerant?

Answer: Both high and low side pressures higher than normal with reduced cooling

An overcharged automotive A/C system typically shows elevated pressures on both the high and low sides. The excess refrigerant floods the system, impairs condenser subcooling, and reduces cooling efficiency despite higher pressures. Technicians may also observe poor compressor performance and abnormally high discharge temperatures with an overcharged system.

PAG oil used in R-134a MVAC systems must be stored and handled carefully for which reason?

Answer: PAG oil is highly hygroscopic and absorbs moisture rapidly from the atmosphere

PAG (polyalkylene glycol) oil is highly hygroscopic — it absorbs moisture from the air very rapidly when exposed. Moisture in refrigerant oil creates acid that damages compressor bearings, valves, and motor windings. Always keep PAG oil containers sealed when not in use, use clean dedicated equipment for oil handling, and minimize air exposure time during oil addition procedures.