Circuit Description
The following DTCs are for the HVAC door actuators:
| • | B0233 -- Air Temperature Actuator |
| • | B0238 -- Mode Actuator |
| • | B0268 -- Recirculation Actuator |
The air temperature and mode actuators are a 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a 0-12 volt linear-ramped signal to command the actuator movement. The 0 and 12 volt control values represent the opposite limits of the actuator range of motion. The values in between 0 and 12 volts correspond to the positions between the limits.
When the HVAC control module sets a commanded, or targeted, value, the control signal is set to a value between 0-12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a new commanded value is needed.
The recirculation actuator is a 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit is either grounded or opened during normal operation. If the control circuit is grounded, then the shaft rotates in the opposite direction than it would if the circuit was opened. The actuator shaft rotates until the limit is reached. If the module needs to reverse the direction of rotation, then the control circuit's state is reversed. The open circuits are held at ignition 3 voltage from the actuator. The module will maintain the control circuit's state until a new position is needed.
Conditions for Running the DTC
| • | The ignition is turned ON. |
| • | DTC B1327 must not be current. |
Conditions for Setting the DTC
The HVAC actuator door control circuit is shorted to ground or shorted to battery voltage for more than 2 seconds.
Action Taken When the DTC Sets
Control of the HVAC actuator door position will be disabled.
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC control module no longer detects a failure. |
| • | The history DTC clears after 50 fault-free ignition cycles. |
| • | Use the scan tool in order to clear the DTCs. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The HVAC actuator can be driven to one of two positions using the command keys on the scan tool. The scan tool displays module output as a percentage of maximum control voltage. It does not indicate true actuator or door position.
-
This step verifies that the HVAC actuator is receiving the control voltage.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | |||
1 | Did you perform the HVAC Diagnostic System Check? | Go to Step 2 | |
Does the drive shaft of the HVAC actuator rotate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Does the voltage change? | Go to Step 5 | Go to Step 4 | |
4 | Test the door control circuit of the appropriate HVAC actuator for a 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 9 | Go to Step 6 |
5 | Inspect for poor connections at the harness connector of the appropriate HVAC 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 9 | Go to Step 7 |
6 | Inspect for poor connections at the harness connector of the HVAC control module. 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 9 | Go to Step 8 |
7 | Replace the appropriate HVAC actuator. Refer to the following: Did you complete the replacement? | Go to Step 9 | -- |
8 | Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
