CFC Automotive Air Conditioning Service 5 — Questions and Answers
Question 1: Why is nitrogen used to leak-test an automotive A/C system after repair rather than refrigerant?
- Nitrogen is cheaper and will not release ODS if the test reveals additional leaks (Correct answer)
- Nitrogen improves system cooling performance during testing
- Nitrogen reacts with moisture to signal leaks
- Nitrogen pressurizes the system faster than refrigerant
Correct answer: Nitrogen is cheaper and will not release ODS if the test reveals additional leaks
Using nitrogen for pressure testing prevents refrigerant release if additional leaks are found, and nitrogen is inert and inexpensive.
Question 2: A vehicle owner asks if they can purchase R-134a in cans smaller than 2 lbs to top off their own car's A/C. Under current EPA rules:
- Yes, small consumer cans are freely available without restriction
- No — purchase of any refrigerant requires Section 609 certification
- Small cans under 2 lbs were restricted for sale to uncertified consumers starting in 2018 (Correct answer)
- Small cans may be purchased but only at licensed auto parts stores
Correct answer: Small cans under 2 lbs were restricted for sale to uncertified consumers starting in 2018
EPA regulations effective January 2018 restrict the sale of small refrigerant containers (under 2 lbs) of R-134a and substitute refrigerants to Section 609-certified technicians only.
Question 3: When recharging an automotive A/C system, the technician should charge by:
- Sight glass observation alone
- Weight using a calibrated refrigerant scale to the manufacturer's specified charge (Correct answer)
- Pressure readings only, targeting 35 psi low side
- Feel — the low-side line should be cold to the touch
Correct answer: Weight using a calibrated refrigerant scale to the manufacturer's specified charge
Charging by weight to the manufacturer's specification is the most accurate method and prevents both undercharge and overcharge.
Question 4: Which organization certifies technicians under EPA Section 609 through an approved certification program?
- NHTSA (National Highway Traffic Safety Administration)
- Refrigerant testing organizations approved by the EPA, such as MACS or ASE (Correct answer)
- Manufacturers of refrigerant only
- State DMV offices
Correct answer: Refrigerant testing organizations approved by the EPA, such as MACS or ASE
EPA-approved certifying organizations such as MACS Worldwide and ASE administer the Section 609 certification exams.
Question 5: An evaporator core is found to be leaking. After recovery and repair, the system should be evacuated to at least:
- 500 microns (Correct answer)
- 1,000 microns
- 2,500 microns
- 5,000 microns
Correct answer: 500 microns
Best practice after opening an automotive A/C system for repair is to evacuate to 500 microns or lower to ensure all moisture and non-condensables are removed.
Question 6: R-1234yf is classified as mildly flammable. What ASHRAE safety classification does it carry?
- A1
- A2L (Correct answer)
- A3
- B2L
Correct answer: A2L
R-1234yf carries the A2L safety classification — low toxicity (A) and mildly flammable with a low burning velocity (2L).
Question 7: A shop that sells or distributes refrigerant for MVAC service is required to sell only to:
- Anyone who presents a valid driver's license
- Section 609 certified technicians, verified before sale (Correct answer)
- Licensed auto repair shops regardless of technician certification
- Customers with vehicles older than 1995
Correct answer: Section 609 certified technicians, verified before sale
Distributors and retailers must verify that purchasers hold valid Section 609 certification before selling refrigerant for MVAC service.
CFC Automotive Air Conditioning Service 5
Why is nitrogen used to leak-test an automotive A/C system after repair rather than refrigerant?