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

Step

Action

Value(s)

Yes

No

Caution: Refer to Radiator Cap Removal Caution in the Preface section.

 

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 action?

--

System OK

Go to Step 4

4

Inspect the drive belts for tension or damage.

Are the drive belts OK?

--

Go to Step 6

Go to Step 5

5

Correct any problem with the drive belts.

Did you complete the action?

--

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 8

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 cap as needed.

Did you complete the repair?

--

System OK

Go to Step 10

10
  1. Turn the air conditioning (A/C) switch OFF on vehicles equipped with 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 for airflow from the vent outlet.

Is there 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 minimum to maximum?

--

Go to Step 12

Go to Blower Motor Malfunction

12
  1. Turn the A/C switch OFF.
  2. Set the temperature lever to full hot.
  3. Set the blower motor switch on maximum speed.
  4. With the engine sufficiently cool, 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 problems:
    2. • Restriction in the cooling system
    • Failed water pump impeller
    • Faulty thermostat
  2. Make repairs to the cooling system, as needed.

Did you complete the repairs?

--

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?

Go to Heating, Ventilation, and Air Conditioning

Go to Step 15

Go to Step 16

15
  1. Inspect the vehicle for cold air leaks at the following locations:
    2. • Dash
    • Heater cases
    • Vents
  2. Inspect under the seat for obstructions.
  3. Repair any leaks or obstructions.

Did you complete the repairs?

--

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 it 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 complete the repair?

--

System OK

--

18
  1. Set the temperature control knob to full hot.
  2. Start the vehicle.
  3. Inspect the temperature of the heater inlet hose and the heater outlet hose by feel.

Is the air temperature around the hoses within the specified value?

27-31°C (80-88°F)

Go to Step 19

Go to Step 22

19

Inspect the thermostat.

Is the thermostat installed and seated properly?

--

Go to Step 20

Go to Step 21

20

Replace the thermostat.

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 hot and the heater outlet hose warm?

--

System OK

Go to Step 25

25

Replace the heater core.

Did you complete the replacement?

--

System OK

--

26

Recheck the system using the Control Settings/Correct Results tests.

Did you complete the action?

--

System OK

Go to Step 27

27

Inspect for airflow from the defroster or the vent outlets.

Is there high airflow from the defroster or vent outlets?

--

Go to Step 28

Go to Step 29

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

Did you complete the repair?

--

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 complete the repair?

--

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 30

Go to Blower Motor Malfunction

32

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

Are there any obstructions?

--

Go to Step 30

Go to Step 30

33

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

Did you complete the repair?

--

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.

Did you complete the repair?

--

System OK

--

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

Did you complete the repair?

--

System OK

--