B0252 - HVAC System - Manual

Schematic:

CIRCUIT DESCRIPTION
The HTR/DEF/AC door motor is an electronic actuator stepper motor with a feedback potentiometer. The IPM determines the position of the door motor based on the voltage from the potentiometer. When the airflow is from the panel, the voltage is high. When the airflow is from the defrost outlet, the voltage is low. The IPM controls the HTR/DEF/AC door motor position to direct airflow from the outlets selected by the vehicle occupants.

CONDITIONS FOR RUNNING THE DTC
The ignition is turned ON.

CONDITIONS FOR SETTING THE DTC
^ The IPM detects the signal circuit is less than 0.03 V (2 counts) or greater than 4.95 V (253 counts).

ACTION TAKEN WHEN THE DTC SETS
^ A default value of 2.50 V (128 counts) will be used for the sensor data by the IPM.
^ The air inlet door will be set to the outside air position.
^ The IPM will only direct airflow from either the panel or defrost outlets.

CONDITIONS FOR CLEARING THE DTC
^ The DTC will become history if the IPM no longer detects a failure.
^ The history DTC will clear after 50 fault free ignition cycles.
^ The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
^ A disconnected or broken door may also set this DTC by allowing the actuator to travel to its internal stops (overtravel condition).
^ Refer to Testing for Intermittent and Poor Connections.

TEST DESCRIPTION

Steps 1-9:

Steps 10-17:

The number(s) below refer to the step number(s) on the diagnostic table.
4. Tests for the proper operation of the circuit in the high voltage range.
5. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
6. Tests for a short to ground in the 5 volt reference circuit.