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:

VISUAL INSPECTION CHART

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

Electrical
- Open Fuse 39 (30 A) or Fuse 21 (10 A).
- 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 concern(s) remain after the inspection, determine the symptom(s) and go to the Symptom Chart. Heating System