GM Service Manual Online
For 1990-2009 cars

Step

Action

Value(s)

Yes

No

1

  1. Remove the heater and A/C control unit.
  2. Disconnect connector C1 from the heater and A/C control unit.
  3. Disconnect the connector from the blower control module.
  4. Test CKT XM112 (BRN/WHT) for a short to voltage. (Turn ON the ignition, leaving the engine OFF, when testing for a short to voltage.)

Did you find a short to voltage on CKT XM112?

--

Go to Step 2

Go to Step 3

2

Repair the short to voltage on CKT XM112 (BRN/WHT).

Did you complete the repair?

--

Go to Step 4

--

3

Replace the blower control module.

Did you complete the replacement?

--

Go to Step 4

--

4

  1. Reassemble any connectors/components removed in previous steps.
  2. Turn the ignition switch to the ON position.
  3. Select AUTO mode on the heater & A/C control.
  4. Cycle through all the blower speeds.

Do all the blower speeds operate properly?

--

System OK

Go to Step 5

5

Replace the heater & A/C control unit.

Did you complete the replacement?

--

Go to Step 6

--

6

Operate the system for which the symptom occurred.

Is the symptom still present?

--

--

System OK