Circuit Description
The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of an electric motor and a potentiometer. The potentiometer inside the door actuator allows the module to monitor the current position of the actuator drive shaft. The module supplies a 5-volt source voltage to the potentiometer on the 5-volt reference circuit. The module supplies ground to the potentiometer through the low reference circuit. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes.
| • | Air flow position feedback circuit refers to the mode actuator. |
| • | Temperature control 1 feedback circuit refers to the driver air temperature actuator. |
| • | Temperature control 2 feedback circuit refers to the passenger air temperature actuator. |
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B0130 Air Flow Position Command Circuit Range |
| • | DTC B0414 Temperature Control 1 Feedback Circuit |
| • | DTC B0424 Temperature Control 2 Feedback Circuit |
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control module detects the door position signal circuit is less than 7 counts or greater than 250 counts for 1 minute.
Action Taken When the DTC Sets
The HVAC control module uses only the minimum and maximum door positions.
Conditions for Clearing the DTC
| • | The DTC becomes history when the HVAC control module no longer detects the condition that set the DTC. |
| • | The history DTC will clear after 50 fault-free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | 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 | |||||||||
2 |
Does the actual parameter of the appropriate actuator change? | -- | Go to Step 3 | Go to Step 4 | ||||||||
3 | Is the voltage difference between the actual parameter and the commanded parameter of the appropriate actuator less than the specified value? | 0.3 V | Go to Step 7 | Go to Step 6 | ||||||||
Does the test lamp illuminate then turn OFF in both directions? | -- | Go to Step 13 | Go to Step 5 | |||||||||
5 | Test the control A circuit and control B circuit of the appropriate actuator for the following:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 | ||||||||
6 | Inspect the appropriate HVAC door and appropriate HVAC actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 13 | ||||||||
7 |
Does the volt meter display near the specified value? | 5 V | Go to Step 8 | Go to Step 12 | ||||||||
8 | Using a DMM measure the signal circuit. Does the DMM display near the specified value? | 5 V | Go to Step 9 | Go to Step 11 | ||||||||
9 | Connect a DMM between the 5-volt reference circuit and the low reference circuit. Does the DMM display near the specified value? | 5 V | Go to Step 13 | Go to Step 10 | ||||||||
10 | Test the low reference circuit of the appropriate actuator for the following:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 | ||||||||
11 | Test the signal circuit of the appropriate actuator for the following:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 | ||||||||
12 | Test the 5-volt reference circuit of the appropriate actuator for the following:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 | ||||||||
13 | 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 . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||||
14 | Replace the appropriate HVAC actuator. Refer to the appropriate replacement procedure: Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||||
15 | 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 . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | ||||||||
16 | Replace the appropriate HVAC control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||||
17 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||||
