batich

30 minutes ago, 1990LS400 said:

The first thing I would check are the drive belts.  Maybe the belt(s) driving the AC compressor and water pump are slipping.

I was thinking of this too. How to check the belts for slipping?

2 minutes ago, Mike B. said:

Your condenser fan is not working. Either the electric fan has failed or the relay may not be working. It works as you drive because you get airflow over the condensor, when you are not moving no airflow and this causes head pressure to rise until it shuts off the compressor. I'd venture a guess that both are related, I can't remember anymore but based on your symptoms I'm guessing it has a single fan so it pulls double duty. It isn't working so airflow over the condenser and radiator is insufficient.

Mike! It was my first guess too. Until I tried to rev up the engine up to 2500 RPM  IN NEUTRAL. In place. Not in driving. And the air flow became COLD. At 1000 RPM it is warm.

Please advise!

1993 Lexus ES300. 

In the idle on low RPM  AC blows warm air. On a higher RPM or while moving - the AC becomes cold.

Also the car overheats after 45 minutes with AC on.  Without AC it does not overheat. I am not sure if these two events are related.

Please assist!