GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2001 🢒 Regal (China) 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Too Hot in Vehicle - Auxiliary

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 auxiliary HVAC control module connector must be connected during this step.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: The temperature cannot be adjusted, or the heating is insufficient.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

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 recirculation switch in the recirculation position.

Does the recirculation door move to the recirculation position?

--

Go to Step 6

Go to Air Recirculation Malfunction

6
  1. Place the blower motor switch in the maximum speed position.
  2. Place the A/C switch in the A/C position.
  3. Place the air 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 22

Go to Step  8

8
  1. Disconnect the auxiliary HVAC control module.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the voltage from the ignition-3 voltage circuit of the auxiliary HVAC control module to the ground circuit of the auxiliary HVAC control module.

Does the voltage measure greater than specified value?

12 V

Go to Step 10

Go to Step  9

9

Measure the voltage from the ignition-3 voltage circuit of the auxiliary HVAC control module to a good ground.

Does the voltage measure greater than specified value?

12 V

Go to Step 13

Go to Step 12

10
  1. Observe the drive shaft of the auxiliary air temperature actuator.
  2. Place the auxiliary air temperature switch from the coldest position to the warmest position.

Does the auxiliary air temperature actuator drive shaft rotate at all?

--

Go to Step 11

Go to Step 14

11

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

    • A misaligned auxiliary air temperature actuator. Refer to Auxiliary Temperature Valve Actuator Replacement .
    • Broken or binding linkages or auxiliary air temperature door
    • An obstruction that prevents the air temperature door from operating within it's full range of motion
    • Missing seals to the auxiliary air temperature door
    • Misaligned seals to the auxiliary air temperature door

Did you find and correct the condition?

--

Go to Step 22

Go to Step 18

12

Test the ignition-3 voltage circuit of the auxiliary HVAC control module for short to ground, 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 22

Go to Step 19

13

Test the ground circuit of the auxiliary HVAC control module 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 22

Go to Step 19

14

Test the ignition-3 voltage circuit of the auxiliary 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 22

Go to Step 15

15

Test the ground circuit of the auxiliary 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 22

Go to Step 16

16

Test the auxiliary air temperature door position signal circuit of the auxiliary air temperature actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 17

17

Important: Ensure that the auxiliary HVAC control module connector is connected during this step in order to avoid misdiagnosis.

  1. Disconnect the Auxiliary air temperature actuator.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the voltage from the auxiliary air temperature door position signal circuit of the auxiliary air temperature actuator to a good ground.
  4. Place the auxiliary 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 18

Go to Step 19

18

Inspect for poor connections at the harness connector of the auxiliary 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 22

Go to Step 20

19

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 22

Go to Step 21

20

Replace the auxiliary air temperature actuator. Refer to Auxiliary Temperature Valve Actuator Replacement .

Did you complete the replacement?

--

Go to Step 22

--

21

Replace the auxiliary HVAC control module. Refer to Auxiliary Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

--

Go to Step 22

--

22

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2