[Rev]

There's not really any way to know without charging to operational pressures and then analyzing with gauges. If the low pressure readings and high pressure readings are not within spec, then the compressor could be bad. Then again, as mentioned earlier, it could be just a leak somewhere resulting in low pressures.

In a nutshell, you will have to have it checked by an AC shop. You can't even buy the refrigerant / oil charge to work on it yourself without a permit.

Rev