Heating and Defrosting

1. Verify the customer's concern by operating the manual heater controls to duplicate the condition.
2. Inspect to determine if one of the following mechanical or electrical concerns apply:

Mechanical
- Loose, misrouted or damaged vacuum lines.
- Misadjusted or broken A/C temperature cable.
- Broken or leaking vacuum control motor.
- Improper A/C heater function selector switch.
- Damaged circuitry.

Electrical
- Blown Fuse 17 (30A).
- Circuitry open/shorted.
- Heater control inoperative.
- Blower motor inoperative.

3. If inspection reveals obvious concern(s) that can be readily identified, service as required.
4. If the concerns remain after the inspection, determine the symptoms and go to the Symptom Chart. Heating System Diagnosis