With the sensor cleaned and installed I ran the diagnostics again and all was ok. So I then tested the A/C for leaks, and pressure.

Although the system had no leaks and A/C compressor engaed ok, there was not enough pressure in the system which lead me back to the compressor. After talking the owner, a NEW compressor was ordered along with receiver/dryer. After replacing those item the A/C is now up and running and blowing nice and cold.