Toyota Repair: AC problems, toyota celica, low pressures

Question
yes i recently replaced my compressor on my 200 toyota celica gts because it had locked up after fill the system with freon it was working great for about 2 days the quit and the AC light on dash started flashing I noticed the next morning at 600 am when i left for work that the AC was working agian but when i came out for lunch it was not and the light was flashing I read about a TSB that said the clutch relay could be the  cause and i replaced that same thing. i thought that maybe it was the pressure switch because of how it would work with the temp outside being cooler but when it got hot it would not and i know temp can effect pressure so i replaced the trianary pressure switch and it worked but when i came out the next day it was back to the working in the morning but not once it got hot can you give me some kind of idea.

Answer
You've done about everything you can do yourself, you're going to have to have the actual a/c line pressures tested, the compressor may be shutting off to either to high or too low pressures or the may be a restriction in the system, possibly the expansion valve or even a bad compressor.