GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Optra 🢒 HVAC 🢒 HVAC - Manual 🢒 Too Cold in Vehicle

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: Component Connector End Views

1

Verify the customer's complaint.

Are the customer's concerns verified?

Go to Step 2

System OK

2

Inspect the coolant level.

Is the coolant level correct?

Go to Step 4

Go to Step 3

3

Add coolant as needed.

Did you complete the repair?

System OK

Go to Step 4

4

Inspect the timing belt for tension or damage.

Are the drive belts OK?

Go to Step 6

Go to Step 5

5

Correct any problem with the timing belts.

Did you find and correct the condition?

System OK

Go to Step 6

6

Inspect the coolant hoses for leaks or kinks.

Are the coolant hoses OK?

Go to Step 8

Go to Step 7

7

Repair any problem with the coolant hoses.

Did you complete the repair?

System OK

Go to Step 9

8

Inspect the surge tank cap.

Is the surge tank cap OK?

Go to Step 10

Go to Step 9

9

Repair or replace the surge tank caps, as needed.

Did you find and correct the condition?

System OK

Go to Step 10

10
  1. Turn the A/C switch OFF on vehicles equipped with air conditioning (A/C).
  2. Set the blower motor switch on maximum speed.
  3. Set the heater control to full hot.
  4. Turn the ignition ON.
  5. Inspect the airflow from the heater outlet.

Is the heavy airflow from the heater outlet?

Go to Step 11

Go to Step 26

11

Inspect for a change in the airflow at various blower speeds.

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

Go to Step 12

Go to Blower Motor Malfunction

12
  1. Turn the A/C switch OFF.
  2. Set the temperature lever to full.
  3. Set the blower motor switch on maximum speed.
  4. When the engine has sufficiently cooled, remove the surge tank cap.
  5. Start the vehicle and idle the engine.
  6. Watch for the flow of the coolant.

Is the coolant flow visible?

Go to Step 14

Go to Step 13

13
  1. Inspect for the following conditions:
    2. • Restriction in the cooling system
    • Failed water pump impeller
    • Faulty thermostat
  2. Make repairs to the cooling system, as needed.

Did you find and correct the condition?

System OK

Go to Step 14

14
  1. Install the surge tank 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 given in the table?

Go to Step 15

Go to Step 16

15
  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 find and correct the condition?

System OK

--

16
  1. Turn the ignition OFF.
  2. Turn the temperature control knob to full cold, then rapidly to full hot.
  3. Listen for the sound of the temperature door slam just before the door reaches the end of the travel range of the control knob.

Does the door slam?

Go to Step 18

Go to Step 17

17
  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 find and correct the condition?

System OK

--

18
  1. Set the temperature control knob to full hot.
  2. Start the vehicle.
  3. Feel the heater inlet hose and the heater outlet hose. Verify that the air temperature around the hoses is at least 29°C (84°F).

Is the heater inlet hose warmer than the heater outlet hose?

Go to Step 19

Go to Step 22

19

Inspect the thermostat. Refer to Thermostat Diagnosis .

Is the thermostat installed and seated properly?

Go to Step 20

Go to Step 21

20

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Did you complete the replacement?

System OK

--

21

Reinstall the thermostat.

Did you complete the repair?

System OK

--

22

Inspect the heater hoses for proper installation.

Are the heater hoses reversed?

Go to Step 23

Go to Step 24

23

Reinstall the heater hoses properly.

Did you complete the repair?

System OK

--

24
  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 the heater outlet hose

Is the heater inlet hose warmer than the heater outlet hose?

System OK

Go to Step 25

25

Replace the heater core.

Did you complete the replacement?

System OK

--

26

Verify the system using the Control Settings/Correct Results tests. Refer to Air Delivery Improper .

Did you find and correct the condition?

System OK

Go to Step 27

27

Inspect for airflow from the defroster or the vent outlets.

Is the airflow high from the defroster or vent outlets?

Go to Step 28

Go to Step 29

28
  1. Inspect the heater door at the floor and inspect the vent door to verify the proper airflow and the proper operation.
  2. Repair the doors as required.

Did you find and correct the condition?

System OK

--

29

Switch the mode knob to defrost.

Is the defroster airflow OK?

Go to Step 30

Go to Step 31

30
  1. Remove the heater outlet and inspect for obstructions.
  2. Remove any obstructions in the heater outlet.

Did you find and correct the condition?

System OK

--

31

Inspect for airflow change at various blower speeds.

Does the blower speed increase as the control is turned from 1 to 4?

Go to Step 32

Go to Blower Motor Malfunction

32

Inspect for obstructions in the system at the blower inlet and at the air filter.

Did you find any obstructions?

Go to Step 33

Go to Step 34

33

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

Did you find and correct the condition?

System OK

--

34
  1. Set the blower on maximum speed.
  2. Rotate the temperature control from full hot to full cold.
  3. Listen for an airflow change.

Does the airflow change?

Go to Step 35

Go to Step 36

35
  1. Inspect the following aspects of the temperature door:
    2. • Travel
    • Cables
    • Linkage
    • Control
  2. Verify the accuracy of the temperature control at full hot.

Is the repair complete?

Go to Step 1

--

36
  1. Inspect the system for any obstruction between the blower and the system outlets.
  2. Remove any obstruction.

Did you find and correct the condition?

Go to Step 1

--