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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Alero Export 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Too Cold in Vehicle

Too Cold in Vehicle Oldsmobile

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 HVAC control assembly 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 mode switch in any position except OFF.
  3. Place the blower control in each speed position.

Does the blower motor operate at all?

--

Go to Step 3

Go to Blower Motor Inoperative

3

Does the blower motor operate correctly, (provide sufficient airflow) for each speed position?

--

Go to Step 4

Go to Blower Motor Malfunction

4
  1. Start the engine.
  2. Place the mode switch in the vent position.
  3. Place the blower motor switch in the maximum speed position.
  4. Place the outside air switch in the ON position.
  5. Place the recirculation switch in the ON position.

Does the recirculation door operate properly?

--

Go to Step 5

Go to Air Recirculation Malfunction

5

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 18

Go to Step 6

6
  1. Start the engine.
  2. Place the mode switch in the OFF, VENT or HEAT positions.

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 7

7
  1. Observe the air temperature actuator drive shaft.
  2. Adjust the air temperature switch.

Does the air temperature actuator drive shaft rotate at all?

--

Go to Step 8

Go to Step 9

8

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 .
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within it's 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 18

Go to Step 9

9

Test the ignition 3 voltage circuit of the 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 18

Go to Step 10

10

Test the ground circuit of the 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 18

Go to Step 11

11

Test the air temperature door position signal circuit of the 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 18

Go to Step 12

12

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

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the air temperature door position signal circuit of the 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?

12 V at cold 0 V at hot

Go to Step 15

Go to Step 13

13

Inspect for poor connections at the harness connector of the 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 18

Go to Step 13

14

Inspect the air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

15

Inspect for poor connections at the harness connector of the HVAC control assembly. 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 18

Go to Step 17

16

Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement .

Did you complete the replacement?

--

Go to Step 18

--

17

Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

--

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2

Too Cold in Vehicle Pontiac

Test Description

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

  1. The specified values are from the Heating Performance Diagnostic.

    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

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 mode switch in any position except OFF.
  3. Place the blower motor switch in each speed position.

Does the blower motor operate at all?

--

Go to Step 3

Go to Blower Motor Inoperative

3

Does the blower motor operate correctly, (provide sufficient airflow), for each speed position?

--

Go to Step 4

Go to Blower Motor Malfunction

4

Inspect the cooling system for the following:

  1. Low coolant level.
  2. Loose or worn accessory drive belt.
  3. Leaking or kinked radiator or heater hoses.
  4. Missing radiator filler cap.
  5. Improper radiator filler cap operation.
  6. Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 5

5
  1. Start the engine.
  2. Place the A/C request switch in the OFF position.
  3. Place the blower motor switch in the OFF position.

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 6

6
  1. Observe the drive shaft of the air temperature actuator.
  2. Adjust the air temperature switch.

Does the air temperature actuator drive shaft rotate at all?

--

Go to Step 7

Go to Step 8

7

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 .
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within it's 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 17

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

8

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

Did you find and correct the condition?

--

Go to Step 17

Go to Step 9

9

Test the ground circuit of the 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 17

Go to Step 10

10

Test the air temperature door control signal circuit of the 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 17

Go to Step 11

11

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

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the air temperature door control signal circuit of the air temperature actuator to a good ground.
  3. Adjust the air temperature switch from Cold to Hot.

Does the voltage measure within the specified values with a smooth transition between cold and hot?

12 V at cold 0 V at hot

Go to Step 13

Go to Step 12

12

Inspect for poor connections at the harness connector of the 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 17

Go to Step 13

13

Inspect the air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

14

Inspect for poor connections at the harness connector of the HVAC control assembly. 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 17

Go to Step 16

15

Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement .

Did you complete the replacement?

--

Go to Step 17

--

16

Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

--

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2