CFC System Charging & Evacuation 4 — Questions and Answers
Question 1: What is the purpose of performing a standing vacuum test after evacuation?
- To verify the refrigerant charge weight is correct
- To confirm the system holds vacuum with no leaks or moisture present (Correct answer)
- To measure the system's operating superheat
- To test the compressor's pumping efficiency
Correct answer: To confirm the system holds vacuum with no leaks or moisture present
A standing vacuum test isolates the system from the pump and monitors the micron reading over time to verify the absence of leaks and significant moisture.
Question 2: When must a technician use recovery equipment before opening a CFC or HCFC system for repair?
- Only when the system charge exceeds 50 pounds
- Only for systems using refrigerants with an ozone depletion potential above 0.5
- Always, regardless of charge size, when the system contains a regulated refrigerant (Correct answer)
- Only if the system is commercially owned
Correct answer: Always, regardless of charge size, when the system contains a regulated refrigerant
EPA Section 608 requires refrigerant recovery before opening any system containing a regulated refrigerant, regardless of the charge size.
Question 3: A technician charges a split system by subcooling method. What measurement is needed to calculate the correct charge?
- Outdoor ambient temperature and indoor wet bulb temperature
- Liquid line temperature and liquid line saturation pressure/temperature (Correct answer)
- Suction superheat and discharge superheat
- Compressor amperage and voltage
Correct answer: Liquid line temperature and liquid line saturation pressure/temperature
The subcooling method requires measuring the liquid line temperature and comparing it to the saturation temperature at the liquid line pressure to calculate actual subcooling.
Question 4: What color are DOT-approved recovery cylinders painted to distinguish them from refrigerant supply cylinders?
- All yellow with a gray collar
- Gray with a yellow collar (Correct answer)
- All green
- All white with a red stripe
Correct answer: Gray with a yellow collar
Recovery cylinders are standardized with a gray body and yellow collar (top) to distinguish them from manufacturer supply cylinders.
Question 5: Which of the following would cause a system to be overcharged after a charging-by-superheat procedure?
- The indoor unit filter was heavily clogged during charging (Correct answer)
- The outdoor ambient temperature was below 65°F during charging
- The technician set superheat 5°F higher than the target
- The system had a dirty condenser coil
Correct answer: The indoor unit filter was heavily clogged during charging
A clogged filter reduces airflow across the evaporator, artificially raising superheat readings and causing the technician to add excess refrigerant.
Question 6: Under EPA Section 608, technicians who violate refrigerant venting prohibitions are subject to fines of up to how much per day per violation?
- $1,000
- $5,000
- $44,539 (Correct answer)
- $100,000
Correct answer: $44,539
EPA Section 608 violations can result in civil penalties of up to $44,539 per day per violation (periodically adjusted for inflation).
Question 7: What is the recommended minimum hose length when connecting a vacuum pump to minimize the effect of hose volume on evacuation time?
- Use the shortest possible hoses to reduce system volume and speed evacuation (Correct answer)
- Use hoses at least 6 feet long to prevent oil backstreaming
- Hose length has no effect on evacuation speed
- Use hoses exactly 12 feet long per industry standard
Correct answer: Use the shortest possible hoses to reduce system volume and speed evacuation
Shorter, large-diameter hoses reduce internal volume and flow resistance, allowing the vacuum pump to evacuate the system faster and to a deeper level.
CFC System Charging & Evacuation 4
What is the purpose of performing a standing vacuum test after evacuation?