Ok, I bought the retrofit kit for my 1993 Explorer, now when I open my hood I see 2 black tops that lead to the AC lines, One of them is on top of what looks to be the condenser on the left side of the motor. The other is on the far right side of the motor near the Radiator hoses but looks as if it is near the fan. Which one is the low pressure side? I have the cans to recharge the AC.

I need to find out which side is the low pressure side so I can drain the old coolent and add the new coolent.