Underneath my Nissan Quest, I can see that the line
going from the A/C compressor to the rear of the car
is leaking oil.

If I simply were to make sure that I do not turn
on the rear A/C, is there a valve between the front
and rear line that will prevent Freon from leaking
from the unit? If so, I'd rather just not use
the rear A/C so I dont have to pay for repairs.