GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION:

    • The rear auxiliary blower motor MED speed will not operate.
    • Vehicle is equipped with heat only (C36).

1

Did you review the HVAC blower operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms

2

  1. Place the ignition switch in the RUN position.
  2. Place the auxiliary blower motor switch in the MED position.

Does the blower motor operate?

--

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

Go to Step 3

3

  1. Disconnect the auxiliary blower motor medium speed relay.
  2. Connect a J 35616-200 unpowered test lamp between auxiliary blower motor medium speed relay connector cavity C1 for CKT 1542 (RED) and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 9

4

Connect a J 35616-200 unpowered test lamp between auxiliary blower motor medium speed relay connector cavity C2 for CKT 341 (BRN) and ground.

Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 10

5

  1. Disconnect the auxiliary blower motor resistor.
  2. Connect a J 39200 digital multimeter (DMM) between auxiliary blower motor medium speed relay connector cavity A2 and auxiliary blower motor resistor connector cavity C for CKT 1072 (LT BLU). Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 6

Go to Step 11

6

Connect a J 39200 DMM between auxiliary blower motor resistor pin C and pin D. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 7

Go to Step 13

7

Connect a J 39200 DMM between auxiliary blower motor medium speed relay connector cavity A1 for CKT 1925 (RED) and ground. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 14

Go to Step 8

8

  1. Disconnect the auxiliary blower motor switch.
  2. Connect a J 39200 DMM between auxiliary blower motor switch pin F and pin B. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 12

Go to Step 15

9

Repair the open in CKT 1542 (RED) between splice S412, and the auxiliary blower motor medium speed relay connector.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

10

Repair the open in CKT 341 (BRN) between splice S405 and the auxiliary blower motor medium speed relay connector.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

11

Repair the open in CKT 1072 (LT BLU) between the auxiliary blower motor medium speed relay connector and the auxiliary blower motor resistor connector.

Refer to Wiring Repairs in wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

12

Repair the open in CKT 1925 (RED)/63 (TAN) between the auxiliary blower motor medium speed relay connector and the auxiliary blower motor switch connector.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

13

Replace the auxiliary blower motor resistor.

Refer to Auxiliary Blower Motor Resistor Replacement .

Did you complete the repair?

--

Go to Step 16

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14

Replace the auxiliary blower motor medium speed relay.

Did you complete the repair?

--

Go to Step 16

--

15

Replace the auxiliary blower motor switch.

Refer to Control Assembly Replacement - Auxiliary .

Did you complete the repair?

--

Go to Step 16

--

16

Operate the auxiliary blower motor in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3