I believe it is under the air filter housing.
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.
The low-side port is located next to the compressor. It will have a cap on it. This is very visible..and will be where you charge your system. Your charging adaptor will only fit the low-side anyway. follow the directions to your charging kit carefully.
The Low side line attaches to the compressor on the driver side of compressor. The charging port faced forward. The high pressure port faces up.
The low side charging port is located high up, near the firewall, on the driver's side, right by the brake master cylinder.
On the passenger side near the fire wall. Coming out of the fire wall you will first see the high side port then the expansion value the next port is the low side port. You will know for sure because the charging hose will only fit on the low side port. You can also see a diagram of this on the link below. Just follow the icon "Find your cars low side port."
the service port is on top the rec-drier on the right side fire wall, its hard to find,
I had the same problem. It is on the right side of the firewall under the heater box. CT
there is a high side charging port up top and a low side underneath the car on the compressor.
I finally found it myself under an electrical connection, on top of the dryer.
It is on the top righthand side at the back of the engine compartment.
On my Focus it is inside the fender liner of the right front wheel.
low-side charging port, located on top of the accumulator/drier, on the passenger's side firewall under the hood.