Troubleshooting Hints

Start Diagnostics Here
Perform the checks listed below 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 50.

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 or voltage check with a system disconnected. These circuits may he 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.

SYSTEM DIAGNOSIS
Perform the System Check first and then refer the appropriate diagnostic charts. System Check - Air Delivery & Temperature Controls