Before you start servicing the air conditioning system, have it evacuated of the refrigerant. This will cost about fifty dollars, if lucky; a service shop might do it for free. Once evacuated, and not under any more pressure, you can start undoing the air conditioning system. The air conditioning system is pressurized at a hundred and thirty pounds per square inch. This is why you need to make sure the service crew evacuates the system, and depressurizes it too, and this is for your safety.
Recommended parts to be replaced are the suction line hoses, orifice filter, accumulator, and if the compressor seems bad, replace too. Parts are inexpensive compared to what a service shop would charge to do the job. When replacing the compressor, you need to install refrigerant oil to the compressor, follow the compressor instructions.
When trying to find a stubborn leak, there is dye that you place in the system to find tiny leaks in seals and o rings.
After you have your new parts installed, install a new serpentine belt, or air conditioning belt, this a good time for belt replacement. Now it is time to recharge your air conditioning system. Buy a recharging gauge and the correct refrigerant for your system. This gauge is around thirty dollars and refrigerant is around five dollars a can. The parts store will tell you how many cans of refrigerant you will need, it is an approximate number. The true gauge is once the gauge is hooked to the car and the refrigerant / Freon can is draining into the system. Then you will know by the gauge, how many cans will be needed. You can always take back what you do not use.
Now the gauge comes with a set of instructions that will walk you through installing the refrigerant back into your system, it is not hard. This will test to see if your system can maintain the right pressure for operation. Also you can see if you have a leak in the system with the gauge. With a certain amount of refrigerant / Freon your gauge should indicate an adequate reading, if not you have a leak still. If you need to depressurize the air conditioning again, you will need to have your service shop evacuate the system for you.
When your system meets your approval, all problem leaks are fixed, take your automobile back to the repair shop for a final air conditioning vacuum and charge. Every time you open the air conditioning system up, it needs to be vacuumed, to rid itself of moisture, that harms the internal air conditioning components. This extra step, will keep your air conditioner in your vehicle longer longer.