Troubleshooting Hints - Without A/C

PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS
1. If the Heater Control Assembly is completely inoperative, check for poor connections at Heater Control Assembly connector C1.
2. Check for missing or damaged connector seals at the Blower Motor Resistor and Blower Motor High Speed Relay.
3. Check HTR-A/C Fuse if the Blower Motor is inoperative. If open, check for short to ground through CKT 341.
4. Check for vacuum supply to the Solenoid Box.
^ 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. Without A/C