GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Century 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Too Hot in Vehicle

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.

    2.

  2. The voltage will vary between 0-12 volts during normal operation. The HVAC control module connector must be connected during this step.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The temperature cannot be adjusted, or the cooling is insufficient during A/C operation.

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch in each speed position.

Does the blower motor operate in any of the speed positions?

--

Go to Step 3

Go to Blower Motor Inoperative

3

Does the blower motor operate at the desired speeds?

--

Go to Step 4

Go to Blower Motor Malfunction

4

When the A/C is ON, does the customer concern occur?

--

Go to Step 5

Go to Step 7

5
  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Place the mode switch in the MAX position.

Does the recirculation door move to the recirculation position?

--

Go to Step 6

Go to Air Delivery Improper

6
  1. Place the blower motor switch in the maximum speed position.
  2. Place the mode switch in the MAX position.
  3. Place the temperature switch in the coldest position.

Does the A/C compressor operate?

--

Go to Step 7

Go to HVAC Compressor Clutch Does Not Engage

7

Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 20

Go to Step  8

8
  1. Observe the drive shaft of the left and right air temperature actuator.
  2. Place the air temperature switch from the coldest position to the warmest position.

Does the air temperature actuator drive shaft rotate at all?

--

Go to Step 9

Go to Step 10

9

Inspect the air temperature door and the air temperature actuator for the following conditions:

    • A misaligned air temperature actuator--Refer to Air Temperature Actuator Replacement - Right Side and Air Temperature Actuator Replacement - Left Side .
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within its full range of motion
    • Missing seals to the air temperature door
    • Misaligned seals to the air temperature door

Did you find and correct the condition?

--

Go to Step 20

Go to Step 10

10

Test the ignition 3 voltage circuit of the suspect air temperature actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 11

11

Test the ground circuit of the suspect air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 12

12

Test the suspect air temperature door control circuit of the air temperature actuator for the following:

    • An open
    • A high resistance
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 13

13

Test the ignition 3 voltage circuit of the HVAC control module for the following:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 14

14

Test the ground circuit of the HVAC control module for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 15

15

Important: The HVAC control module connector must be connected to correctly perform this test.

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the suspect air temperature door control circuit of the suspect air temperature actuator to a good ground.
  3. Place the air temperature switch from the coldest position to the warmest position.

Does the voltage measure within the specified values with a smooth transition between COLD and HOT?

0-12 V

Go to Step 17

Go to Step 16

16

Inspect for poor connections at the harness connector of the suspect air temperature actuator. 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 20

Go to Step 18

17

Inspect for poor connections at the harness connector of the HVAC control module. 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 20

Go to Step 19

18

Replace the suspect air temperature actuator. Refer to Air Temperature Actuator Replacement - Right Side or Air Temperature Actuator Replacement - Left Side .

Did you complete the replacement?

--

Go to Step 20

--

19

Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2