The electronic climate control (ECC) modules (front or
rear) serves as an interface between the passenger and the air delivery system.
The ECC modules compares passenger selections with environmental conditions
and will adjust air delivery accordingly.
The following air delivery modes are available:
| • | External air circulation |
| • | Internal air circulation |
The ECC modules requires two voltage sources in order to operate. Voltage
is available at all times through the RADIO fuse).
When the ignition switch is in the RUN position, voltage is available
through the HVAC I fuse).
A path to ground for the ECC modules is provided to grounds G200/G410.
The ECC modules receives inputs from the following temperature sensors:
| • | The inside air temperature sensor. |
| | A fan located internally to the inside air temperature sensor housing
continually draws passenger compartment air over the sensor increasing accuracy
of the temperature reading. The HVAC I fuse applies voltage for the fan
motor when the ignition switch is in the RUN position. A path to ground
for the fan motor is provided to ground G202. |
| • | The outside air temperature sensor. |
| • | The sun load temperature sensor. |
| • | The upper discharge air temperature sensor (front or rear). |
| • | The lower discharge air temperature sensor (front or rear). |
The ECC modules will use the sensor information in order to determine
how much airflow to the heater core is required and will adjust the air temperature
valve accordingly. The air temperature valve is located internally to the
heater core housing. The position of the air temperature valve is reported
to the ECC modules by the air temperature valve sensor and motor. The HVAC
I fuse applies voltage for the air temperature valve sensor and motor
when the ignition switch is in the RUN position.
Operation of the air temperature valve sensor and motor is supported
by the following circuits:
| • | An 5 volt reference circuit. |
| • | An ground reference circuit. |
| • | An signal return path circuit. |
| • | An motor drive signal circuit. |
The ECC modules will control the actuation of individual motors of the
HVAC assembly in order to direct air to the appropriate outlets. The HVAC
I fuse applies voltage for the HVAC assembly when the ignition switch is
in the RUN position. With voltage available the ECC modules will complete
the current path to ground.
