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

Test Description

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

  1. 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 cooling is insufficient during A/C operation.

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

Inspect the cooling system for the following conditions:

  1. A low coolant level
  2. A loose or worn accessory drive belt
  3. A leaking radiator hose or heater hose
  4. A kinked radiator hose or heater hose
  5. A missing radiator cap pressure seal
  6. A leaking radiator cap

Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 5

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

Place the A/C switch in the OFF.

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 7

7
  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 9

Go to Step  8

8

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 12

Go to Step 11

9
  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 10

Go to Step 13

10

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 21

Go to Step 17

11

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 21

Go to Step 12

12

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 21

Go to Step 18

13

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 21

Go to Step 14

14

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 21

Go to Step 15

15

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 21

Go to Step 16

16

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 17

Go to Step 18

17

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 21

Go to Step 19

18

Inspect for poor connections at the harness connector of the auxiliary 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 21

Go to Step 20

19

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

Did you complete the replacement?

--

Go to Step 21

--

20

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

Did you complete the replacement?

--

Go to Step 21

--

21

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2