GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Vivant 🢒 HVAC 🢒 HVAC - Manual 🢒 Too Cold in Vehicle

Step

Action

Value(s)

Yes

No

Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Inspect the coolant level.
  2. Inspect the serpentine accessory drive belt for tension or damage.
  3. Inspect the coolant hoses for leaks or kinks.
  4. Inspect the coolant reservoir cap. Refer to Pressure Cap Testing .
  5. Repair or replace any defected parts as needed.

Did you complete the repair?

--

System OK

Go to Step 3

3
  1. Set the A/C switch OFF on the vehicles equipped with air conditioning.
  2. Set the temperature control knob to full hot.
  3. Set the blower motor switch on 4.
  4. Turn ON the ignition.
  5. Inspect the airflow from the vent outlet.

Is there a heavy airflow from the vent outlet?

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Go to Step 4

Go to Step 18

4

Inspect the change in the airflow at various blower speeds.

Does the blower speed increase as the switch is turned from 1-4?

 

Go to Step 5

Go to Blower Motor Malfunction

5
  1. With the engine sufficiently cool, remove the coolant reservoir cap.
  2. Set the blower motor switch on 4.
  3. Set the temperature control knob to full hot.
  4. Start the engine and idle the engine.
  5. Watch for the flow of the coolant.

Is the coolant flow visible?

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Go to Step 9

Go to Step 6

6

Inspect the thermostat. Refer to Thermostat Diagnosis .

Is the thermostat installed and seated properly?

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Go to Step 7

Go to Step 8

7

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Did you complete the repair?

--

System OK

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8

Install the thermostat.

Did you complete the repair?

--

System OK

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9
  1. Install the coolant reservoir cap.
  2. With the ignition ON, allow the engine to warm up for about 20 minutes. Drive the vehicle at 48 km/h (30 mph).
  3. Use a thermometer to measure the ambient air temperature and the discharge air temperature at the heater outlet.

Does the heater output meet the minimum values.

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Go to Step 10

Go to Step 11

10
  1. Inspect the vehicle for cold air leaks at the following locations:
    2. • The dash
    • The heater cases
    • The vents
  2. Inspect under the seat for obstructions.
  3. Repair any leaks or obstructions.

Did you complete the repair?

--

System OK

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11
  1. Turn OFF the ignition.
  2. Turn the temperature control knob to full cold, then rapidly to full hot.
  3. Listen for a second at the end of the travel range of the control knob.

Does the door slam?

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Go to Step 13

Go to Step 12

12
  1. Inspect the following aspects of the temperature door:
    2. • Travel
    • Cables
    • Linkage
  2. Verify the accuracy of the temperature controls at full hot.
  3. Verify the accuracy of the temperature controls at full cold.

Did you complete the repair?

--

System OK

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13
  1. Set the temperature door to full hot.
  2. Start the vehicle.
  3. Inspect the temperature of the heater inlet hose and the heater outlet hose by feel. The air temperature around the hoses should be at least 20°C (84°F).

Is the heater inlet hose hot and heater outlet hose warm?

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Go to Step 19

Go to Step 14

14

Inspect heater hoses for proper installation.

Are heater hoses reversed?

--

Go to Step 15

Go to Step 16

15

Install the heater hoses properly.

Did you complete the repair?

--

System OK

Go to Step 17

16
  1. Back flush the heater core.
  2. Drain the cooling system.
  3. Replace the coolant.
  4. Warm the engine to an average operating temperature.
  5. Feel the heater inlet hose and outlet hose.

Are the heater inlet hose hot and the heater outlet hose warm?

--

System OK

Go to Step 17

17

Replace heater core. Refer to Heater Core Replacement .

Did you complete the repair?

--

System OK

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18

Inspect the system using the Control Setting/Correct Results tests. Refer to Air Delivery Improper .

Did you complete the repair?

--

System OK

Go to Step 19

19

Inspect the airflow from the defroster or the vent outlets.

Is there high airflow form the defroster or vent outlets?

--

Go to Step 20

Go to Step 21

20

Inspect the heater door at the floor and the vent door to get proper airflow, verify proper operation, and repair as required.

Did you complete the repair?

--

System OK

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21

Push the defroster knob.

Is the defroster airflow OK?

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Go to Step 22

Go to Step 23

22
  1. Remove the heater outlet and inspect for obstructions.
  2. Remove any obstructions in the heater outlet.

Did you complete the repair?

--

System OK

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23

Inspect for obstructions in the system at the blower inlet and the air filter, if the vehicle is equipped with one.

Are there any obstructions?

--

Go to Step 24

Go to Step 25

24

Remove the obstructions in the system at the blower inlet or replace a clogged filter.

Did you complete the repair?

--

System OK

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25
  1. Set the blower on 4.
  2. Slide the temperature control knob from full hot to full cold.
  3. Listen for an airflow change.

Does the airflow change?

--

Go to Step 26

Go to Step 27

26
  1. Inspect for the following aspects of the temperature door:
    2. • Travel
    • Cable
    • Linkage
    • Control
  2. Verify the accuracy of the temperature controls at full hot.
  3. Verify the accuracy of the temperature controls at full cold.

Did you complete the repair?

--

Go to Step 1

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27
  1. Inspect the system for any obstruction between the blower and the system outlets.
  2. Remove any obstructions.

Did you complete the repair?

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Go to Step 1

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