GM Service Manual Online
For 1990-2009 cars only

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The specified values are from the A/C System Performance Test.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: Auxiliary air temperature can not be adjusted from one or both auxiliary controls or auxiliary cooling is insufficient.

1

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

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

Important: The auxiliary A/C system cannot request A/C compressor operation. The mode switch must be positioned to MAX, NORM, BI-LEVEL, BLEND or DEFROST on the HVAC control module to provide cooled airflow through the auxiliary system.

Does the HVAC control module operate and provide sufficient cooling?

Go to Step 3

Go to Too Hot in Vehicle

3

  1. Turn ON the ignition, with the engine OFF.
  2. Place the Heat and/or A/C auxiliary blower motor switch in each speed position.

Does the auxiliary blower motor operate at all?

Go to Step 4

Go to Auxiliary Blower Motor Inoperative

4

Does the auxiliary blower motor operate correctly for each speed position?

Go to Step 5

Go to Auxiliary Blower Motor Malfunction

5

Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test .

Did you find and correct the condition?

Go to Step 8

Go to Step 6

6

Inspect for poor connections at the harness connector of the auxiliary heater blower motor switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 7

7

Replace the auxiliary heater blower motor switch. Refer to Heater Control Blower Switch Replacement .

Did you complete the replacement?

Go to Step 8

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8

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2