Its Important to remember

After your visual inspection, ALWAYS use your gauges to diagnose refrigerant system problems with the vehicles A/C system. Not your ears, or your nose. You can use your eyes to read the gauges.
The system must have the proper refrigerant charge before you start your diagnostic.
A bad engine fan clutch is the reason most compressors fail.
Finding OIL or DYE does NOT mean that there is a freon leak. A simple SOAP BUBBLE test will confirm if freon is leaking.
Oil is pushed thru the system by the freon. When system is under charged or has a leak it will stop the flow of oil and cause damage to the compressor.
9 out of 10 compressors fail due to other problems with the vehicle.
A properly installed New Compressor replacement will fix half of the other A/C problems with the vehicle.