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 connector.
  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 to the inoperative position.
  5. Using a test light, backprobe between ground and the blower motor resistor connector terminal listed below:
  6. • LO: Terminal B.
    • M1: Terminal A.
    • M2: Terminal D.
    • M3: Terminal C.

Does the test light illuminate?

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Go to Step 3

Go to Step 4

3

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

Has the repair been made and the system rechecked?

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Go to Step 7

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4

  1. Turn the ignition switch to the OFF position.
  2. Keep the blower motor resistor connector disconnected.
  3. Disconnect the heater-A/C control connector C1.
  4. Check for a poor connection or an open in the inoperative circuit listed below: Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  5. • LO: Terminal B.
    • M1: Terminal A.
    • M2: Terminal D.
    • M3: Terminal C.

Is there a poor connector, an open, or a short to ground in the inoperative circuit tested?

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Go to Step 5

Go to Step 6

5

Locate and repair the fault in the circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Step 7

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6

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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7

Verify that the system operates properly.

Does the system operate properly?

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System OK

Go to Symptoms