Chart 1C-1 Insufficient or No Heating

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The H-A/C control sends a voltage through CKT 1199 corresponding to the position of the temperature slide even The H-A/C sends 0 volts in the extreme cold position 12 volts in the extreme hot position or a voltage proportional to any intermediate setting. The electric actuator has an internal potentiometer in it. Using internal feedback from the "POT," the electric actuator can move the temperature valve to its command.

DIAGNOSTIC AIDS

1. Check for proper engine coolant level.

2. Check engine for proper operating temperature approximately 91°C (195°F)). If engine does not reach 91°C (195°F), replace thermostat.

3. With engine at normal operating temperature check heater inlet and outlet hose temperature.

^ Heater inlet hose temperature should be at or near engine operating temperature.

^ Heater outlet hose temperature should be slightly cooler that the heater inlet hose.

^ If heater hose temperatures are incorrect, replace heater core.

4. Inspect plenum area (at base of windshield) for debris or anything that may cause airflow restriction.