The 1990 LS400 I had did the same thing. Light flashed, AC no longer cold, compressor stopped. Had it converted to 134 at a dealer and it ran for another 5 or 6 months then gone again. Had a friend who works at Toyota have his boys check it out and it turned out the compressor had destructed and send metal throughout the system. That's the bad news, now the worse news. In order to replace the system, the dashboard must be removed to access the internal components. Finally, the even worse news (if you can imagine) was the cost to replace was right around $2500 at 3 different places.
I sold the car for $2500 to my friend's son who was driving a ragged out bikini top jeep. He thinks the LS is cool
I of course, still miss the car. Best car I've ever owned..