GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

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

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Go to Step 2

Go to Symptoms

2

Verify that the blower motor is inoperative at any speed.

Does the blower motor operate normally?

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

Go to Step 3

3

Inspect the HVAC fuse 9.

Is the HVAC fuse 9 open?

--

Go to Step 4

Go to Step 5

4

  1. Locate and repair the short to ground in one or more of the following circuits:
  2. • CKT 141 (BRN)
    • CKT 64 (BRN)
    • CKT 63 (TAN)
    • CKT 72 (LT BLU
    • CKT 52 (ORN)
  3. Replace the HVAC fuse 9.

Is the repair complete?

--

Go to Step 18

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5

  1. Turn on the heater and A/C controller mode switch to any position.
  2. Turn the blower switch to one of the following positions:
  3. • LOW
    • MED-1
    • MED-2
  4. Disconnect the blower motor relay.
  5. Turn the ignition switch to the RUN position.
  6. Use a J 39200 Digital Multimeter (DMM) in order to measure the voltage between the blower motor relay connector cavity 87A and ground.

Does the J 39200 DMM display battery voltage?

--

Go to Step 6

Go to Step 13

6

Connect a fused jumper wire between the blower motor relay cavity 87A and cavity 30.

Does the blower motor operate?

--

Go to Step 7

Go to Step 8

7

Replace the blower motor relay.

Is the replacement complete?

--

Go to Step 18

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8

  1. Reconnect the blower motor relay.
  2. Disconnect the blower motor connector.
  3. Using the J 35616-A , construct jumper leads in order to connect blower motor terminal A to connector terminal A and blower motor terminal B to connector terminal B.
  4. Turn the ignition switch to the ON position.
  5. Turn the blower switch to the HIGH position.
  6. Use a J 39200 DMM in order to measure the voltage between the blower motor CKT 65 (PPL) cavity A and battery ground.

Does the J 39200 display battery voltage?

--

Go to Step 10

Go to Step 9

9

Repair the open in CKT 65 (PPL) between the blower motor and the blower motor relay.

Is the repair complete?

--

Go to Step 18

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10

  1. Reconnect the blower motor relay.
  2. Disconnect the blower motor connector.
  3. Using the J 35616-A , construct jumper leads in order to connect blower motor terminal A to connector terminal A and blower motor terminal B to connector terminal B.
  4. Turn the ignition switch to the ON position.
  5. Turn the blower switch to the HIGH position.
  6. Use a J 39200 DMM in order to measure the voltage between the blower motor terminal A (CKT 65) and blower motor terminal B (CKT 850).

Does the J 39200 DMM display battery voltage?

--

Go to Step 11

Go to Step 12

11

Replace the blower motor. Refer to Blower Motor and Fan Replacement .

Is the replacement complete?

--

Go to Step 18

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12

Repair the open in CKT 850 (BLK) between the blower motor and G117.

Is the repair complete?

--

Go to Step 18

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13

  1. Use a J 39200 DMM in order to backprobe the heater and A/C controller connector C2 cavity C to ground.
  2. Measure the voltage.

Does the J 39200 DMM display battery voltage?

--

Go to Step 15

Go to Step 14

14

Repair the open in CKT 141 (BLK) between the heater and A/C controller and the IP fuse block.

Is the repair complete?

--

Go to Step 18

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15

  1. Use a J 39200 DMM in order to backprobe the heater controller connector C2 cavity B to ground.
  2. Measure the voltage.

Does the J 39200 DMM display battery voltage?

--

Go to Step 16

Go to Step 17

16

Repair the open in CKT 64 (BRN) between the heater and A/C controller cavity E connector C4 and cavity B connector C2.

Is the repair complete?

--

Go to Step 18

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17

Replace the heater and A/C controller. Refer to Control Assembly Replacement .

Is the replacement complete?

--

Go to Step 18

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18

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3