which is low pressure service port?

[HelloWorld]

In a 2000 4.4i X5 , which is the low pressure service port for R134a refrigerant charging? the upper service port (near the MAF) or the lower one?

[fast4d]

they have different size fittings. I believe the low pres is the smaller one.

[iop9000]

if it does not fit, then its the wrong one

[HelloWorld]

Thanks!
Some says the low pressure port is the larger one in other forum.

In fact, i am looking for a more definite answer.