1998 Toyota Corolla EVAPORATOR

I recently took my car to two local garages to have problems with my a/c diagnosed. However they both gave me different out comes. One says that my condensor and compressor are shot. (Leaking) when r143a was added the system works fine but in a day or two it all leaks out. The other says that my compressor is fine but the condensor and evaporator is shot. That they both show holes. So I decided to replace everyhting. But I can't seem to find the evaporator anywhere. My only guess is that it is located inside the car near the heater core. If thats the case how did they check that. Please help!