With HVAC System - Automatic - Manual Controls

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS
1. Check A/C Clutch Fuse for an open.
2. Make sure A/C Compressor Clutch and A/C Clutch Relay connectors terminals are free from corrosion.
3. Make sure grounds G109 and G201 are clean and tight.
4. Make sure A/C System has proper refrigerant level. Check for leaks, etc.
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer to General Troubleshooting Procedures). Diagnostic Aids
^ Refer to System Diagnosis. System Diagnosis