a/c service ports?

[djtoothowd]

may be a stupid question or repeat but looking at my a/c lines i see two service ports, two different sizes but they're on the same line about 6 inches from each other. i cant see the low and high side ports being like that. make some sense out of this for me please.

 

[yukonguy]

Is there a fitting between the two like on mine? If so, then in between the two ports is the orifice tube which meters the freon into the evaporator. The high pressure port is before the orifice tube. The low pressure port is after the tube. The fitting between the two gives you access to the orifice tube.

BTW, just joined this morning...great site...looking for answers...trying to help