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

  1. Disconnect the blower motor resistor.
  2. Turn the ignition switch to the RUN position.
  3. Place the heater-A/C control in the VENT position.
  4. Place the blower switch in the OFF position.
  5. Use a test lamp to probe between the following blower motor resistor harness connector terminals and ground:
  6. • LO - B (CKT 60)
    • M1 - A (CKT 63)
    • M2 - D (CKT 72)
    • M3 - C (CKT 73)
    • HI - F (CKT 52)

Does the test lamp light for any test?

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Go to Step 3

Go to Step 6

3

  1. Leave the probe connected to the same terminal that illuminated the test lamp
  2. Disconnect the heater-A/C control connector C 1.

Does the test lamp keep lighted?

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Go to Step 4

Go to Step 5

4

Locate and repair the short to B+ in the affected circuit:

  1. LO - Blower motor terminal B (CKT 60).
  2. M1 - Blower motor resistor harness connector terminal A (CKT 63).
  3. M2 - Blower motor resistor harness connector terminal D (CKT 72).
  4. M3 - Blower motor resistor harness connector terminal C (CKT 73).
  5. HI - Blower motor resistor harness connector terminal F (CKT 52).

Is the repair complete?

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Go to Step 7

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5

Replace the heater-A/C control. Refer to Control Assembly Replacement .

Is the repair complete?

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Go to Step 7

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6

Replace the blower motor resistor. Refer to Blower Motor Resistor Replacement .

Is the repair complete?

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Go to Step 7

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7

Verify that the system operates properly.

Does the system operate properly?

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System OK

Go to Symptoms