Circuit Description
The mode actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The HVAC control module controls the mode door position by sending a control signal to the actuator. The signal's value is dependent upon the desired mode selected by the vehicle occupants. As the actuator moves, the potentiometer produces the actual door position signal that is sent to the HVAC control module. The HVAC control module continues to command the actuator to move until the desired and actual values are equal. The door directs airflow through the outlets as selected by the vehicles occupants.
The HVAC control module commands the actuator through it's full range. The HVAC control module stores the learned minimum and maximum position values. The travel range value is calculated by subtracting the minimum and maximum position values. Then the HVAC control module compares the travel range, minimum and maximum values to calibrated value ranges. If the travel range value is less than or equal to the maximum calibrated limit and greater than or equal to the minimum calibrated limit, then the calibration is considered successful. The HVAC control module continuously compares the actual actuator position to the calibrated minimum and maximum position values.
DTC Descriptors
This diagnostic procedure supports the following DTC:
B0233 Air Flow Control Circuit
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
Conditions for Setting the DTC
| • | Mode actuator position signal is less than 5 counts. |
| • | Mode actuator position signal is more than 194 counts. |
| • | The mode actuators total travel range is less than or greater than the calibrated limits. |
Action Taken When the DTC Sets
| • | The DTC is stored in DTC information. |
| • | The HVAC control module will continue to make use of whatever travel range is still available. |
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
| • | A damaged or broken mode door and or actuator can cause this DTC to set. |
| • | If the Mode actuator travels beyond it's calibrated limits the DTC will set. |
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 |
Does the mode actuator drive shaft rotate for each selected position? | -- | Go to Step 3 | Go to Step 4 | ||||||
3 | Inspect the mode door and the mode actuator for the following:
Did you find and correct the condition? | -- | Go to Step 15 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | ||||||
4 | Test the ignition 3 voltage circuit of the mode actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 5 | ||||||
5 | Test the ground circuit of the mode actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 6 | ||||||
6 | Test the 5-volt reference circuit of the mode actuator for an open, a high resistance, short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 7 | ||||||
7 | Test the mode door position signal circuit of the mode actuator for an open, a high resistance, short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 8 | ||||||
8 | Test the mode door control circuit of the mode actuator for an open, a high resistance, short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 9 | ||||||
9 |
Important: The mode actuator connector and the HVAC controller connector must be connected to correctly perform the test.
Does the mode actuator drive shaft rotate and does the voltage change? | -- | Go to Step 10 | Go to Step 11 | ||||||
10 |
Does the voltage measure near the specified value when airflow moves toward DEF, near the specified value when airflow moves toward FLR, and near the specified value when stationary? | 0 V toward DEF 5 V toward FLR 2.5 V stationary | Go to Step 11 | Go to Step 12 | ||||||
11 | Inspect for poor connections at the harness connector of the mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | ||||||
12 | Inspect for poor connections at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 | ||||||
13 | Replace the mode actuator. Refer to Mode Actuator Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
14 | Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
15 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 | ||||||
