Toyota Repair: A/C PROBLEMS, toyota dealer, two choices

Question
93 CELICA CONVERTIBLE.  A/C WORKS WHEN NOT HOT OUTSIDE BUT FAILS WHEN OUTSIDE TEMPS RISE?  SUGGESTIONS, MY TOYOTA DEALER TELLS ME THAT THE EVAPERATIVE VALVE NEEDS REPLACED AS WELL AS THE DRIER AT A COST OF 775.00.  DO YOU AGREE WITH THIS REPAIR?  THANKS, KEITH

Answer
Although that is a possibility there could be many other things wrong, there is no way I can either agree or disagree with that diagnosis, a/c diagnosis can be involved and requires checking line pressures with gauges and checking for leaks, since I don't have this information you have two choices, either have them go ahead with their recommendations or take it somewhere else to get another opinion.
Sorry, but that's all the help I can give with the information given.