I'm Not exactly sure which one it is exactly but the best way to find out is to take a vacuum gauge and test both of them the one that is sucking in is the one you would use to recharge your ac system.
The low pressure port for the 2003 sable is on the passenger side of the engine compartment. It is right at the firewall made into a hose.
You can find the air conditioning low pressure charging port on top of the air conditioning compressor. The low pressure port will be on the right hand side of the air conditioning compressor.
low side is next to or on conpressor.has blue cap on low side red cap on highside
The low pressure air conditioner port can be found on the top of the air conditioner compressor. The low pressure port should be labeled as such.
Under the hood
Where is the low pressure side AC port on 2006 jetta 1.9 TDIRead more: Where_is_the_low_pressure_side_AC_port_on_2003_jetta_1.9_TDI
You can recharge your 2003 Kia air conditioning system through the low pressure port. Connect your Freon bottle to the low pressure port. Release the Freon into the system.
The high pressure fitting is the larger of the two. The adapters and fittings used to add refrigerant can only fit the low pressure side. I have a 2003 Silverado 2500HD and the low pressure port is just above the accumulator/ dryer on a line that attaches to the fire wall.
You can recharge your air conditioning system by putting Freon into the low pressure port. The low pressure port can be found on top of the air conditioning compressor.
left side on firewall should be on the side of ac condencer
It's located right on the evaporator
You can add air conditioning refrigerant to your 2000 F1 50 pickup truck air conditioning system through the low pressure port. The low pressure port will be on the top of the air conditioning compressor.