Behind the radiator, under the air intake!
The 1999 Ford Ranger low pressure air conditioning valve can be found on the air conditioning compressor. The low pressure valve will be labeled as the low pressure port.
The low pressure valve, on your 1995, Mercury, is located on the top of the air conditioning compressor. The low pressure valve should be labeled.
The 1993 Ford Ranger air conditioning charge valve can be found on the top of the air conditioning compressor. The charge valve will be marked as the low pressure valve.
The 1988 Chevy Corsica air conditioning service valves can be found on top of the air conditioning compressor. The air conditioning service valves are labeled as the low pressure valve and the high pressure valve.
The air conditioning recharge valve on the 2003 Ford Explorer 4.6 is located on the low pressure side of the air conditioning system. Located on the line coming from the accumulator to the compressor is the recharge valve.
BEHIND THE COMPRESER
Depends on the make, model and engine
That sounds like the expansion valve.
Through the schrader valve on the low pressure side of the system.
The evaporator charging valve
It's on the passenger side against the firewall, it has a plastic cap on it with a capital L