MACS 609 Certification Practice Exam

After the first refrigerant recovery process in an HFC-134a A/C system, how long must the system vacuum level remain stable for additional recovery to be deemed unnecessary?

1. 1 minute

2. 2 minutes

3. 3 minutes

4. 5 minutes

The correct answer is: 2 minutes

The correct choice indicates that the system vacuum level must remain stable for a duration of 2 minutes after the first refrigerant recovery process in an HFC-134a A/C system. This requirement is tied to ensuring that there are no significant leaks in the system and that it has been properly evacuated of air and moisture. When performing a refrigerant recovery, the technician needs to monitor the vacuum level to confirm that it holds steady after evacuation. A stable vacuum level for 2 minutes serves as a reliable indicator that the system is airtight and has reached an appropriate vacuum level. If the vacuum level drops during this time, it suggests the presence of a leak or residual refrigerant, indicating that further recovery actions might be necessary. This duration is generally accepted in the industry as a standard time frame for confirming that the vacuum achieved can be relied upon, thus preventing unnecessary complications during the recharging or servicing process that might arise from incomplete evacuation.