GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Express 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Auxiliary Blower Motor Medium Speed Inoperative

Step

Action

Value(s)

Yes

No

1

Was the HVAC Blower Controls System Check performed?

--

Go to Step 2

Go to HVAC Blower Controls System Check

2
  1. Disconnect the auxiliary blower motor medium speed relay connector.
  2. Connect an unpowered test lamp between the auxiliary blower motor high speed relay connector, cavity C1 for CKT 1542 (RED), and ground.

Does the test lamp light?

--

Go to Step 3

Go to Step 13

3
  1. Place the ignition switch in the RUN position.
  2. Connect an unpowered test lamp between the auxiliary blower motor medium speed relay connector, cavity C2 for CKT 341 (BRN), and ground.

Does the test lamp light?

--

Go to Step 4

Go to Step 14

4
  1. Disconnect the connector at the auxiliary blower motor.
  2. Connect a J 39200 between the auxiliary blower motor medium speed relay connector, cavity A2, and the auxiliary blower motor connector, cavity B for CKT 1172 (YEL).

Is continuity present?

--

Go to Step 5

Go to Step 15

5

Is vehicle equipped with a rear HVAC control module?

--

Go to Step 8

Go to Step 6

6
  1. Place the front auxiliary HVAC control module in the MED position.
  2. Connect a J 39200 between the auxiliary blower motor low speed relay connector, cavity A1 for CKT 1925 (RED), and ground.

Is continuity present?

--

Go to Step 16

Go to Step 7

7
  1. Disconnect the front HVAC control module connector.
  2. Connect a J 39200 between the front HVAC control module, pin E, and pin F.

Is continuity present?

--

Go to Step 17

Go to Step 19

8

Does auxiliary blower motor operate from the rear auxiliary HVAC control module?

--

Go to Step 9

Go to Step 11

9
  1. Place the front auxiliary HVAC control module in the MED position.
  2. Connect a J 39200 between the auxiliary blower motor medium speed relay connector, cavity A1 for CKT 1925 (RED), and ground

Is continuity present?

--

Go to Step 16

Go to Step 10

10
  1. Disconnect the front auxiliary HVAC control module.
  2. Connect a J 39200 between the front auxiliary HVAC control module, pin E, and pin B.

Is continuity present?

--

Go to Step 18

Go to Step 19

11
  1. Place the front auxiliary HVAC control module in the REAR CNTL position.
  2. Place the rear auxiliary HVAC control module in the MED position.
  3. Connect a J 39200 between the auxiliary blower motor medium speed relay connector, cavity A1 for CKT 1925 (RED), and ground.

Is continuity present?

--

Go to Step 16

Go to Step 12

12
  1. Disconnect the rear auxiliary HVAC control module connector.
  2. Connect a J 39200 between the rear auxiliary HVAC control module, pin E, and pin B.

Is continuity present?

--

Go to Step 20

Go to Step 21

13

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

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

14

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

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

15

Repair the open in CKT 1172 (YEL) between splice S413 and the auxiliary blower motor medium speed relay connector.

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

16

Replace the auxiliary blower motor medium speed relay.

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

17

Repair the open in CKT 1925 (RED) / 63 (TAN) between the auxiliary blower motor low speed relay connector and the front auxiliary HVAC control module connector.

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

18

Repair the open in CKT 63 (TAN) between the front auxiliary HVAC control module connector and splice S321.

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

19

Replace the front auxiliary HVAC control module.

Refer to Control Switch Replacement - Auxiliary .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

20

Repair the open in CKT 63 (TAN)between the rear auxiliary HVAC control module connector and splice S321

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--

21

Replace the rear auxiliary HVAC control module.

Refer to Control Switch Replacement - Auxiliary .

Is the repair complete?

--

Go to HVAC Blower Controls System Check

--