B0434

CIRCUIT DESCRIPTION
The auxiliary air temperature actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The position of the auxiliary air temperature actuator is based on the auxiliary air temperature door position signal voltage from the potentiometer. The auxiliary HVAC module converts this voltage to a digital signal that can be transmitted over the keyboard display driver (KDD) data bus to the HVAC control module. The HVAC control module contains the logic that controls the operation of the auxiliary air temperature actuator. Whenever the HVAC control modules keep alive memory battery power is interrupted, the HVAC control module will perform a recalibration of the actuators. The HVAC control module will perform a travel range comparison of the calculated minimum and maximum extremes of the actuator to the calibrated minimum and maximum range extremes within the HVAC control module. If the calculated range does not equal the calibrated expected range the actuator will be considered not calibrated and the DTC will set. The HVAC control module will also perform a continuous test on the current feedback value. If the feedback value does not equal or tall within the calibrated range the DTC will set.

CONDITIONS FOR RUNNING THE DTC
^ The ignition is ON.
^ Ignition voltage is between 9-16 volts.
^ The HVAC control modules keep alive memory battery power must be interrupted to run the range check.

CONDITIONS FOR SETTING THE DTC
^ The auxiliary air temperature door position signal is less than 5 counts or greater than 250 counts.
^ The auxiliary air temperature actuators total travel range (max-min) is less than or greater than the calibrated limits.

ACTION TAKEN WHEN THE DTC SETS
^ The HVAC control module will continue to make use of whatever travel range is still available.
^ Each time the ignition switch is turned ON the HVAC control module will recheck the actuator travel range.

CONDITIONS FOR CLEARING THE DTC
^ If the HVAC control no longer detects a failure, then the DTC will become history.
^ The history DTC will clear after 50 ignition cycles without a failure.
^ The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
^ The range fault can only be detected following a check of the actuator travel range. The actuator travel range check can only be initiated by disrupting power to the HVAC control module.
^ The calibration limit is 64-216 counts. An actual range below this limit suggests an obstruction (something stuck in the door limiting travel). An actual range above this limit suggests an over travel condition (damaged or missing foam seals).
^ A damaged or broken auxiliary air temperature door and or actuator can cause this DTC to set.
^ If condition not present refer to Testing for intermittent and Poor Connections in Diagnostic Aids.

TEST

Steps 1-7:

Steps 8-13: