On a 1994 Chevy C1500 5.0 V8 it is the top valve with a black cover next to the coolant resivoir
look for the port with the black cap on it, it's the low pressure port.
The freon port for a 1994 Chevy S-10 with a 4.3L engine is located on the passenger side of the engine bay. The low-pressure service port is typically near the accumulator, while the high-pressure port is closer to the compressor. Make sure to identify the ports correctly, as they are different sizes to prevent accidental connections. Always ensure the system is off before attempting to service the AC system.
The diagnostic port on a 1994 Chevy S-10 is located under the dash, near the hood release. It allows an OBDII code reader to be connected for troubleshooting problems.
on the evaporator / dryer
It is on the accumulator.
You can add Freon to your 1999 Chevy cooling system through the low pressure port. Connect your Freon bottle to the low pressure port and release the Freon into the system.
You can find the air conditioning ports on top of the air conditioning compressor. There will be a low pressure port and a high pressure port.
The 1994 Honda Civic air conditioning low pressure port is located on top of the air conditioner compressor. The low pressure port will have a blue top.
The 1994 Mercedes-Benz low side port can be found on the top of the air conditioner compressor. The low side port will be labeled as the low pressure port.
The smallest with a green cap on it.
The 2002 Chevy Cavalier low side service port can be found on the top of the air conditioner compressor. The low side service port will be labeled as the low pressure port.
It's right above the high pressure port!! :) under the air cleaner box ,