GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Park Avenue 🢒 DTC 🢒 DTC B1341 Air Mix Door #2 Movement Problem

Object Number: 246922 Size: MF
HVAC Components
HVAC Air Delivery/Temperature Control Schematics
Handling ESD Sensitive Parts Notice
Cell 68: Temperature Actuators
Cell 68: Temperature Actuators
Cell 10: WSW, WSW/RFA, HUD, ELC, CR CONT, A/C and HVAC Fuses

Circuit Description

The rear junction block supplies ignition voltage through circuit 141 (BRN). The HCM commands the actuator to move by suppling voltage on the command line circuit 1236 (DK BLU). The command line voltage and motor actions are as follows:

    • 0 volts moves toward full hot.
    • 2.5 volts stops the motor.
    • 5 volts moves toward full cold.

The HCM determines the current position by monitoring the voltage on the feedback circuit 1646 (LT BLU). A feedback potentiometer supplies a regulated 5 volt signal by the HCM on circuit 705 (GRY), and a ground from the HCM circuit 1791 (YEL). The pot is gear driven inside the actuator. The feedback voltage is a function of the motor position with a high voltage of 4-5 volts indicating full cold door position. A low voltage of less then 1 volt indicates the full hot position. Operation of the air mix door actuator can be evaluated through Scan Tool

The right temp door motor is an electronic actuator stepper motor with a feedback potentiometer. The heater and A/C programmer determines the position of the door motor based on the voltage from the potentiometer. When the air flow is cool (heater core bypass), the voltage is low. When the air flow is warm (through the heater core), the voltage is high. The heater and A/C programmer controls the right temp door motor position to maintain the temperature selected by the passenger.

Conditions for Setting the DTC
    • Ignition is ON.
    • The heater and A/C programmer detects the signal circuit is less than 0.88 V (45 counts) or greater than 4.35 V (222 counts).

Action Taken When the DTC Sets
    • A default value of 2.50 V (128 counts) will be used as sensor data by the heater and A/C programmer .
    • The heater and A/C programmer will toggle the actuator between full hot and full cool in an attempt to maintain the temperature selected by the passenger.

Conditions for Clearing the DTC
    • Using a scan tool.
    • A history DTC will clear after 50 fault free ignition cycles.
    • The DTC will become history if the heater and A/C programmer no longer detects a failure.

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 Intermittents and Poor Connections Diagnosis in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Perform the HVAC Diagnostic Symptom Check before continuing with the diagnosis of this DTC.

    2.

  2. This test allows the scan tool to check the working specs of the right temp door.

    3.

  3. This step checks the ground circuit of the passenger air mix actuator.

    4.

  4. This step inspects the heater and A/C programmer for a poor harness connection.

Step

Action

Value(s)

Yes

No

1

Was the HVAC diagnostic system check performed?

--

Go to Step  2

Go to Diagnostic System Check

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the Right Temp Door Actual parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the Right Temp Door Actual parameter is within the specified range?

0.88 - 4.88 V

Go to Diagnostic Aids

Go to Step  3

3
  1. With a scan tool, command the Right Temp Door Position from Hot to Cold.
  2. With a scan tool, observe the Right Temp Door Actual parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the Right Temp Door Actual parameter changes when the Right Temp Door Position is commanded from Hot to Cold?

--

Go to Step  12

Go to Step  4

4
  1. Turn OFF the ignition.
  2. Disconnect the passenger air mix actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Right Temp Door Actual parameter.

Does the scan tool indicate that the Right Temp Door Actual parameter is greater than the specified value?

4.35 V

Go to Step  5

Go to Step  9

5
  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the signal circuit of the right temp door position sensor and the motor ground circuit of the passenger air mix actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Right Temp Door Actual parameter.

Does the scan tool indicate that the Right Temp Door Actual parameter is greater than the specified value?

0.88 V

Go to Step  6

Go to Step  10

6
    • Turn OFF the ignition.
    • Disconnect the fused jumper wire.
    • Connect a 3 amp fused jumper wire between the 5 volt reference circuit of the right temp door position sensor and the signal circuit of the right temp door position sensor.
    • Turn ON the ignition, with the engine OFF.
    • With a scan tool, observe the the Right Temp Door Actual parameter.

Does the scan tool indicate that the Right Temp Door Actual parameter is greater than the specified value?

4.35 V

Go to Step  8

Go to Step  7

7

Test the 5 volt reference circuit of the right temp door position sensor for a short to ground

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  17

Go to Step  14

8

Test the 5 volt reference circuit of the right temp door position sensor for a short to voltage, a high resistance or an open.

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  17

Go to Step  13

9

Test the signal circuit of the right temp door position sensor for a short to ground.

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  17

Go to Step  14

10

Test the signal circuit of the right temp door position sensor for a short to voltage, a high resistance or an open.

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  17

Go to Step   11

11

Test the motor ground circuit of the passenger air mix actuator for a high resistance, or an open.

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  17

Go to Step  14

12

Inspect the air mix door for a condition allowing excessive travel of the actuator.

Did you find and correct the condition?

--

Go to Step  17

Go to Step  13

13

Inspect for poor connections at the harness connector of the passenger air mix actuator.

Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  17

Go to Step  15

14

Inspect for poor connections at the harness connector of the heater and A/C programmer.

Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  17

Go to Step  16

15

Replace the passenger air mix actuator.

Refer to Air Mix Actuator Replacement - Passenger .

Did you complete the replacement?

--

Go to Step  17

--

16

Replace the heater and A/C programmer.

Refer to Programmer Replacement .

Did you complete the replacement?

--

Go to Step  17

--

17
  1. Use the scan tool in order to clear the DTC's.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step   2

System OK