With HVAC System - Manual

1. Check the HVAC CTRL and HVAC HI Fuses in the fuse block for an open.
2. Make sure G200 is clean and tight.
3. If the Heater-A/C Control is completely inoperative, check for poor connections at Heater-A/C Control connector C1.
^ 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.