Here is a Check Sheet for inspecting Air Conditioning problems that we at RepairPal have put together. Using a systematic approach is the best way to really find the cause of an A/C problem.
https://repairpal.com/estimator/air-conditioning-diagnosis-cost
RepairPal Certified shops can diagnose and repair your 1997 Toyota Avalon. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.