Where do I add Freon in a 2001 Ford Focus ZX3

what you found was the high pressure line red cap on it look for a blue capon low pressure side.should be at back nearpassenger side fire wall

Best to let expert do this with gauge to much freon will blow seal in compressor or bust hose you may even need the system pumped down let expert do it

The low pressure line is under neath the passenger side headlight behind the front bumper cover , you can access it through the wheel well over on the passenger side underneath the front of the car .... >>>> You will see the accumulator there and the low pressure feed line with the the ac port is built into that line .... follow the ac lines in the front of the engine near the ac compresssor and you will find it