During the process of refrigerant recovery, the technician should operate the recovery unit until the system pressure has been reduced to a vacuum, then
a. immediately close the valve in the service lines and remove the lines from the vehicle
b. immediately close the valve in the service line and charge the system
c. *recover to a vacuum of 4 inches of mercury, isolate the system and wait 5 minutes to see that the system holds the vaccum
d. open the shut­off valves which must be located within 4 inches of the service ends

i have learnt about the business report to determine the database requirements.

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