Yes as mentioned above, if the sensor cant be replaced or is unavailable (which is hard to believe because these compressors can be rebuilt), then you are left with little choice. Whenever you open the system for extended period of time, you have to replace the drier. Whenever you replace the compressor, for the sake of the new compressor, you should replace the drier. If you have to replace the compressor and the drier, you may as well replace the sensors on the drier if they have not been replaced ever. If the system is flushed, then the system can be filled accurately with oil otherwise there is some guessing involved. Otherwise, your failure does not sound like an internal compressor failure, so flushing may not be necessary.

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Saumil S. Patel