Daewoo Nubira. Manual — part 177

7A – 4

I

HEATING AND VENTILATION SYSTEM

DAEWOO V–121 BL4

DIAGNOSIS

HEATER SYSTEM

INSUFFICIENT HEATING OR DEFROSTING

CAUTION : The cooling system is pressurized when hot. Injury can result from removing the surge tank cap be-
fore the engine is sufficiently cool.

Step

Action

Value(s)

Yes

No

1

Verify the customer’s complaint.
Are the customer’s concerns verified?

Go to Step 2

System OK

2

Check the coolant level.
Is the coolant level correct?

Go to Step 4

Go to Step 3

3

Add coolant, as needed.
Is the repair complete?

System OK

Go to Step 4

4

Check 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.
Is the repair complete?

System OK

Go to Step 6

6

Check 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.
Is the repair complete?

System OK

Go to Step 8

8

Check the surge tank cap. Refer to Section 1D, En-
gine Cooling.
Is the surge tank cap OK?

Go to Step 10

Go to Step 9

9

Repair or replace the surge tank cap as needed.
Is the repair complete?

System OK

Go to Step 10

10

1. Turn the A/C OFF on vehicles equipped with

air conditioning.

2. Turn the blower motor switch to 4.
3. Turn the heater control to full hot.
4. Turn the ignition ON.
5. Check for airflow from the vent outlet.

Is there heavy airflow from the vent outlet?

Go to Step 11

Go to Step 26

11

Check 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

Electrical”

12

1. Turn the A/C OFF.
2. Turn the temperature control knob to full hot.
3. Turn the blower motor switch to 4.
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

HEATING AND VENTILATION SYSTEM 7A – 5

DAEWOO V–121 BL4

Step

No

Yes

Value(s)

Action

13

1. Check for the following problems:

S

Restriction in the cooling system.

S

Failed water pump impeller.

S

Faulty

thermostat.

2. Make repairs to the cooling system, as needed.

Are the repairs complete?

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 approximately 20 minutes. Drive the ve-
hicle 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
specified?

Refer to ”Heat-

er Temperature

Specifications”

Go to Step 15

Go to Step 16

15

1. Check the vehicle for cold air leaks at the fol-

lowing locations:

S

Dash.

S

Heater

cases.

S

Vents.

2. Check under the seat for obstructions.
3. Repair any leaks or obstructions.

Are the repairs complete?

System OK

16

1. Turn the ignition OFF.
2. Turn the temperature control knob from full

cold to full hot.

3. Listen for the sound of the temperature door

slam just before reaching the end of the travel
range of the control knob.

Does the door slam?

Go to Step 18

Go to Step 17

17

1. Check the following aspects of the temperature

door:

S

Travel.

S

Cables.

S

Linkage.

2. Verify the accuracy of the temperature controls

at full hot.

3. Verify the accuracy of the temperature controls

at full cold.

Is the repair complete?

System OK

18

1. Turn the temperature control knob to full hot.
2. Start the vehicle.
3. Check the temperature of the heater inlet hose

and the heater outlet hose by feel. The air tem-
perature around the hoses should be at least
29

°

C (84

°

F).

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

Go to Step 19

Go to Step 22

19

Check the thermostat. Refer to 1D, Engine Cooling.
Is the thermostat installed and seated properly?

Go to Step 20

Go to Step 21

7A – 6

I

HEATING AND VENTILATION SYSTEM

DAEWOO V–121 BL4

Step

No

Yes

Value(s)

Action

20

Replace the thermostat. Refer to Section 1D, En-
gine Cooling.
Is the repair complete?

System OK

21

Reinstall the thermostat.
Is the repair complete?

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.
Is the repair complete?

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 tem-

perature.

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.
Is the repair complete?

System OK

26

Recheck the system using the ”Control Settings/
Correct Results” tests. Refer to ”Improper Air Deliv-
ery or No Mode Shift” in this section.
Is the repair complete?

System OK

Go to Step 27

27

Check for airflow from the defroster or the vent out-
lets.
Is there high airflow from the defroster or vent out-
lets?

Go to Step 28

Go to Step 29

28

Check the heater door at the floor and the vent door
to get the proper airflow, verify proper operation, and
repair, as required.
Is the repair complete?

System OK

29

Turn 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 check for ob-

structions.

2. Remove any obstructions in the heater outlet.

Is the repair complete?

System OK

31

Check 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

Electrical”

32

Check 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 33

Go to Step 34

33

Remove the obstructions in the system at the blower
inlet or replace a clogged filter.
Are the repairs complete?

System OK

HEATING AND VENTILATION SYSTEM 7A – 7

DAEWOO V–121 BL4

Step

No

Yes

Value(s)

Action

34

1. Turn the blower motor switch to 4.
2. Turn the temperature control knob 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. Check the following aspects of the temperature

door:

S

Travel.

S

Cables.

S

Linkage.

S

Control.

2. Verify the accuracy of the temperature control

at full hot.

Is the repair complete?

Go to Step 1

36

1. Check the system for any obstruction between

the blower and the system outlets.

2. Remove any obstruction.

Is the repair complete?

Go to Step 1

BLOWER ELECTRICAL

Step

Action

Value(s)

Yes

No

1

Verify the customer’s complaint.
Are the customer’s concerns verified?

Go to Step 2

System OK

2

Does the blower run at any speed?

Go to Step 14

Go to Step 3

3

1. Disconnect the power connector from the blow-

er motor under the dashboard on the passen-
ger’s side of the vehicle.

2. Turn the ignition ON.
3. Turn the blower ON.
4. Test the voltage on the connector. The terminal

connected to the PPL wire is positive and the
terminal connected to the BLK wire is negative.

Is this voltage within the specified range?

11–14 v

Go to Step 4

Go to Step 5

4

Replace the blower motor.
Is the repair complete?

System OK

5

Check fuse EF2 in the engine fuse block.
Is the fuse blown?

Go to Step 6

Go to Step 7

6

1. Turn the ignition ON.
2. Use a short detector to locate the following

possible shorts:

S

From the fuse panel to the blower speed

switch.

S

From the blower speed switch to the heater

resistor block.

S

From the heater resistor block to the blow-

er motor.

S

From the blower speed switch to the blower

HI relay.

3. Repair any short.
4. Replace any blown fuse.

Is the repair complete?

System OK