In this case since you are not having a shop do this just cahrge that baby up. Remeber that charging the system is in stages. Charge while at idle with A/C on until you get like 2 cans in there. Make sure compressor engages full time then slowly fill with freon while reving the engine to 2k rpms. With compressor fully engaged at 2k rpms pressure on low side should be at least 35 psi. When you shut the car off after filling do not check pressure as it will equalize and peg the gage. Checking pressure at idle is the same will be pegged until compressor engages.