The correct amount is specified by the manufacturer and is usually found:
* On a sticker: Look for a sticker under the hood, often near the radiator or air conditioning components. This sticker will specify the refrigerant type and the charge amount in ounces or grams.
* In the owner's manual: Your owner's manual might also list this information.
* Using a refrigerant identification chart: A professional AC technician will use a chart that lists the correct refrigerant and charge amount based on the vehicle's make, model, and year.
Attempting to add refrigerant yourself without knowing the exact amount is dangerous and can damage the system. Overcharging can cause serious problems, including compressor failure. It's best to have a qualified technician perform the service.