Smokvica26

Hi, This is the issue. My ac stopped working and I'm getting code 33 which is Open in air mix damper position sensor circuit or open or short in air mix servomotor circuit or, air mix servomotor locked. Now I replaced the compressor last year and can somebody please tell me where is this Servo Motor or sensor cuircuit located on my car and how do I check if it is bad? I have 1992 LS400. Thanks