GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you review the HVAC 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 ON 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 in order to backprobe between the blower motor resistor harness connector terminal listed below and ground:
  6. • LO - Terminal B (circuit 60)
    • M1 - Terminal A (circuit 63)
    • M2 - Terminal D (circuit 72)
    • M3 - Terminal C (circuit 73)
    • HI - Terminal F (circuit 52)

Does the test light turn on when checking each terminal?

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Go to Step 3

Go to Step 6

3

  1. Leave the test light connected to same terminal that turned test light on.
  2. Disconnect the heater-A/C control connector C1.

Does the test lamp light?

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Go to Step 4

Go to Step 5

4

Repair the short to B+ in the following circuit: Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

    • LO - Blower motor resistor harness connector terminal B (circuit 60)
    • M1 - Blower motor resistor harness connector terminal A (circuit 63)
    • M2 - Blower motor resistor harness connector terminal D (circuit 72)
    • M3 - Blower motor resistor harness connector terminal C (circuit 73)
    • HI - Blower motor resistor harness connector terminal F (circuit 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 in Heating, Ventilation, and Air Conditioning .

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