GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 DeVille 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Air Delivery Improper - Auxiliary

Test Description

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

  1. This step tests for an auxiliary blower motor that does not operate regardless of the desired blower motor speed.

    2.

  2. This step tests for an auxiliary blower motor that operates, yet does not accurately respond to the desired blower motor speed.

    3.

  3. The measured voltage should be near the specified value for each mode position.

Mode Position

Value

Vent

0.0-1.0 V

Bi-Level

2.0-4.0 V

Floor

5.0-7.0 V

Off

B+

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: Air does not flow correctly from the auxiliary air distribution outlets.

1

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the auxiliary blower motor switch in the OFF position.

Is the auxiliary blower motor OFF?

Go to Step 3

Go to Auxiliary Blower Motor Always On

3

Place the auxiliary blower motor switch in each speed position.

Does the auxiliary blower motor operate in each speed position?

Go to Step 4

Go to Auxiliary Blower Motor Inoperative

4

Does the auxiliary blower motor operate at the desired speed?

Go to Step 5

Go to Auxiliary Blower Motor Malfunction

5

Place the auxiliary mode switch in each mode position.

Does the air flow from the correct air distribution outlets in each selected mode position?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Disconnect the auxiliary mode actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the auxiliary mode actuator supply voltage circuit and ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 9

7

Connect a test lamp between the auxiliary mode actuator supply voltage circuit and the low reference circuit of the auxiliary mode actuator.

Does the test lamp illuminate?

Go to Step 8

Go to Step 10

8

  1. Measure the voltage from the auxiliary mode door control circuit to a good ground.
  2. Place the auxiliary mode switch in each mode position. Refer to Test Description.

Does the voltage measure near the specified values for each mode selected?

Go to Step 12

Go to Step 11

9

Test the auxiliary mode actuator supply voltage circuit for an open, short to ground or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

10

Test the low reference circuit of the auxiliary mode actuator for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

11

Test the auxiliary mode door control circuit for an open, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

12

Inspect the auxiliary mode door and the auxiliary mode actuator for the following conditions:

    • A misaligned auxiliary mode actuator. Refer to Auxiliary Mode Valve Actuator Replacement .
    • Broken or binding linkages or auxiliary mode door
    • An obstruction that prevents the door from operating within its full range of motion
    • Missing seals to the auxiliary mode door
    • Misaligned seals to the auxiliary mode door

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 auxiliary 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 17

Go to Step 15

14

Inspect for poor connections at the harness connector of the auxiliary 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 17

Go to Step 16

15

Replace the auxiliary mode actuator. Refer to Auxiliary Mode Valve Actuator Replacement .

Did you complete the replacement?

Go to Step 17

--

16

Replace the auxiliary HVAC control module. Refer to Auxiliary Heater and Air Conditioning Control Module Replacement .

Did you complete the replacement?

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2