how much is too much freon
You need gauges, and using the sticker under the hood will tell you how much a proper fill is. You have to properly evacuate the system first. Here is a link to what is involved....http://www.wikihow.com/Recharge-the-Air-Conditioner-in-a-Car
If you have to add refrigerant to the system, then it has a leak, the system is closed. Simply adding refrig is a stop gap-temporary fix which gets expensive over time.
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