2004 DAEWOO NUBIRA coolant temperature

5A2 – 94IAISIN AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DTC P1792 Engine Coolant Temperature (ECT) Signal Error
StepActionValue(s)YesNo
11. Turn the ignition OFF.
2. Install the Scan tool.
3. With the engine OFF, turn the ignition switch to
the ON position.
4. Select Clear DTC Information from the Diag-
nostic Trouble Codes Information menu.
5. Clear DTC Information.
6. Perform one vehicle drive cycle.
7. Select Request DTC by Status from the Diag-
nostic Trouble Codes Information menu.
8. Request DTC by Status.
Is DTC P1792 displayed?–Go to Step 2Repair the tem-
porary connec-
tion failure of
connector.
21. Turn the ignition OFF.
2. Disconnect the TCM wiring connector and
ECM wiring connector.
3. Measure the resistance between terminal A17
of the TCM wiring connector and terminal 88 of
the ECM wiring connector.
4. Measure the resistance between terminal A7 of
the TCM wiring connector and terminal 57 of
the ECM wiring connector.
Is the resistance within the values shown?0 WGo to Step 4Go to Step 3
3Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
41. Turn the ignition ON.
2. Measure the voltage of terminal A17.
3. Measure the voltage of terminal A7.
Is the voltage within the values shown?11–14 vGo to Step 5Go to Step 6
5Repair the malfunctioning terminals as necessary.
Is the action complete?–System OK–
61. Replace the TCM.
2. Turn the ignition OFF.
3. Turn the ignition ON.
4. Check if P1792 DTC is set.
Is the DTC set?–Go to Step 7Go to Step 8
7Replace the ECM.
Is the action complete?–Go to Step 8–
81. After the repair, use a scan tool ”clear info”
function and road test the vehicle.
2. Review the ”DTC info”.
Has the last test failed or is the current DTC dis-
played?–Begin diagno-
sis againRepair verified
exit DTC chart

7A – 6IHEATING 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
ActionValue(s)YesNo
1Verify the customer’s complaint.
Are the customer’s concerns verified?–Go to Step 2System OK
2Check the coolant level.
Is the coolant level correct?–Go to Step 4Go to Step 3
3Add coolant as needed.
Is the repair complete?–System OKGo to Step 4
4Check the timing belt for tension or damage.
Are the drive belts OK?–Go to Step 6Go to Step 5
5Correct any problem with the timing belt.
Is the repair complete?–System OKGo to Step 6
6Check the coolant hoses for leaks or kinks.
Are the coolant hoses OK?–Go to Step 8Go to Step 7
7Repair any problem with the coolant hoses.
Is the repair complete?–System OKGo to Step 8
8Check the surge tank cap. Refer to Section 2D, En-
gine Cooling.
Is the surge tank cap OK?–Go to Step 10Go to Step 9
9Repair or replace the surge tank cap as needed.
Is the repair complete?–System OKGo to Step 10
101. 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. Check for airflow from the vent outlet.
Is there heavy airflow from the heater outlet?–Go to Step 11Go to Step 26
11Check 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 12Go to ”Blower
Electrical
(Manual and
Non–A/C)”
121. 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 14Go to Step 13

7A – 28IHEATING AND VENTILATION SYSTEM
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
HEATING AND VENTILATION
SYSTEMS
The base heater system is designed to provide heating,
ventilation, windshield defrosting, side window defogging,
and on some vehicles, heating directly to the rear seat
area.
The heater and fan assembly blower regulates the airflow
from the air inlet for further processing and distribution.
The heater core transfers the heat from the engine coolant
to the inlet air.
The temperature door regulates the amount of the air that
passes through the heater core. The temperature door
also controls the temperature of the air by controlling the
mix of the heated air and the ambient air.
The mode door regulates the flow and the distribution of
the processed air to the heater ducts and to the defroster
ducts.
This console–mounted heating and ventilation panel con-
tains the following:
The Rotary Temperature Control Knob
1. The Rotary Temperature Control Knob
S Actuates by cable.
S Raises the temperature of the air entering the
vehicle by rotation toward the right, or the red
portion of the knob.
2. The Rotary Blower Control Knob
S Turns ON to operate the blower motor at four
speeds.
S Turns OFF to stop the blower.
S Operates completely independently both from
the mode control that regulates the defroster
door and from the temperature control knob.S Changes the fan speed in any mode and at any
temperature setting.
3. The Rotary Mode Control Knob
S Actuates by cable.
S Regulates the air distribution between the wind-
shield, the instrument panel, and the floor vents.
Two Push Knobs
1. The Rear Window Defogger Push Knob
S Controls the rear window defogger.
S Turns ON the rear window defogger when the
push knob is pressed and the indicator lamp is
illuminated.
2. The A/C Push Knob (if the vehicle is equipped with
air conditioning)
S Controls the A/C.
S Turns the A/C ON when the push knob is down.
However, if the blower control knob is OFF, the
A/C system is OFF, regardless of the position of
the A/C knob.
Fresh Air Control Level Or Push Knob
1. The Fresh Air Control Level
S Operates by cable.
S Switches between recirculating passenger
compartment air and bringing outside air into the
passenger compartment.
S Draws in outside air when the lever is moved to
the right.
S Recirculates inside air when the lever is moved
to the left.
2. The Fresh Air Control Push Knob
S Operates by cable.
S Switches between recirculating passenger
compartment air and bringing outside air into the
passenger compartment.
S Draws in outside air when knob is off.
S Recirculates inside air when the knob is down
with the indicator lamp illuminated.

MANUAL CONTROL HEATING, VENTILATION AND AIR CONDITIONING SYSTEM 7B – 51
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
GENERAL INFORMATION
THE V5 A/C SYSTEM
The V5 variable displacement compressor along with the
thermal expansion valve on the evaporator, constitutes a
largely self–regulating system. There is no pressure cycl-
ing switch, no high–pressure cut–off switch and no low–
pressure cut–off switch. The compressor clutch is con-
trolled by the electronic control module (ECM), which
receives data from various engine systems and from a
pressure transducer located in the high–pressure refriger-
ant pipe. In normal operation, the clutch is engaged contin-
uously. Should one of the monitored conditions become
abnormal, the ECM will disengage the compressor clutch
until normal operation is restored. These conditions in-
clude the following:
S Wide–open throttle.
S High engine coolant temperature.
S High engine RPM.
S Refrigerant low pressure.
S Refrigerant high pressure.
The compressor clutch will remain disengaged until nor-
mal operation is established.
SYSTEM
COMPONENTS–FUNCTIONAL
Compressor
All compressors are belt–driven from the engine crank-
shaft through the compressor clutch pulley. The compres-
sor pulley rotates without driving the compressor shaft un-
til an electromagnetic clutch coil is energized. When
voltage is applied to energize the clutch coil, the clutch
plate and hub assembly is drawn rearward toward the
pulley. The magnetic force locks the clutch plate and
pulley together as one unit to drive the compressor shaft.
As the compressor shaft is driven, it compresses the low–
pressure refrigerant vapor from the evaporator into a
high–pressure, high–temperature vapor. The refrigerant
oil which is used to lubricate the compressor is carried with
the refrigerant. Refer to ”V5 Air Conditioning Compressor
Overhaul” in this section.
Condenser Core
The condenser assembly in front of the radiator consists
of coils which carry the refrigerant, and cooling fins that
provide the rapid transfer of heat. The air passing through
the condenser cools the high–pressure refrigerant vapor
and causes it to condense into a liquid.
Expansion Valve
The expansion valve is located with the evaporator core,
on the front passenger side fire wall.
The expansion valve can fail in three different positions:
open, closed, or restricted.
An expansion valve that fails in the open position will result
in a noisy A/C compressor or no cooling. The cause can
be a broken spring, a broken ball, or excessive moisture
in the A/C system. If the spring or the ball are found to be
defective, replace the expansion valve. If excessive mois-
ture is found in the A/C system, recycle the refrigerant.
An expansion valve that fails in the closed position will re-
sult in low suction pressure and no cooling. This may be
caused by a failed power dome or excessive moisture in
the A/C system. If the power dome on the expansion valve
is found to be defective, replace the expansion valve. If ex-
cessive moisture is found in the A/C system, recycle the
refrigerant.
A restricted expansion valve will result in low suction pres-
sure and no cooling. This may be caused by debris in the
refrigerant system. If debris is believed to be the cause, re-
cycle the refrigerant, replace the expansion valve, and re-
place the receiver–dryer.
Evaporator Core
The evaporator is a device which cools and dehumidifies
the air before it enters the vehicle. High–pressure liquid re-
frigerant flows through the expansion tube orifice and be-
comes a low–pressure gas in the evaporator. The heat in
the air passing through the evaporator core is transferred
to the cooler surface of the core, which cools the air. As the
process of heat transfer from the air to the evaporator core
surface is taking place, any moisture or humidity in the air
condenses on the outside surface of the evaporator core
and is drained off as water.
Receiver–Dryer
The sealed receiver–dryer assembly is connected to the
condenser outlet pipe. It acts as a refrigerant storing con-
tainer, receiving liquid, vapor, and refrigerant oil from the
evaporator.
At the bottom of the receiver–dryer is the desiccant, which
acts as a drying agent for the moisture that may have en-
tered the system. An oil bleed hole is located near the bot-
tom of the receiver–dryer outlet pipe to provide an oil re-
turn path to the compressor. The receiver–dryer is
serviceable only as an assembly.
Heater Core
The heater core heats the air before it enters the vehicle.
Engine coolant is circulated through the core to heat the
outside air passing over the fins of the core. The core is
functional at all times and may be used to temper condi-
tioned air in the A/C mode as well as in the heat or the vent
modes.

7D – 8IAUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO V–121 BL4
NO HOT AIR FROM BLOWER
StepActionValue(s)YesNo
1Check the coolant level.
Is the coolant level correct?–Go to Step 3Go to Step 2
2Add coolant as needed.
Is the heater operating?–System OKGo to Step 3
31. Turn the ignition to ON.
2. Observe the temperature indication screen of
the controller.
Does the digit flash on and off?–Go to Step 4Go to Step 5
4Run a self–diagnosis circuit check.
Does the display indicate a defect code?–Go to the table
for the code
that flashesGo to Step 7
5Observe the blower motor operation.
Is the blower motor functioning at all?–Go to Step 6Go to ”Blower
Motor Does
Not Run at All”
6Use the blower push switch to cycle the blower
through its different speeds.
Does the motor function at different speeds?–Go to Step 7Go to ”Code 6
– Power Tran-
sistor Error”
71. Run the blower and operate the MODE push
switch manually.
2. Check for airflow out the various outlets.
Does the air flow from the different outlets as it
should?–Go to Step 9Go to Step 8
81. Remove the heater outlet and check for ob-
structions.
2. Remove any obstructions found.
Is the heater operating?–System OKGo to Step 9
9Observe the air mix door (AMD) motor while chang-
ing the temperature setting from 18 to 32°C (64 to
90°F) and then from 32 to 18°C (90 to 64°F).
Is the AMD motor functioning properly?–Go to Step 10Go to”Code 4 –
Air Mix Door
Error”
10Check the coolant hoses for leaks or kinks.
Are the coolant hoses in good condition?–Go to Step 12Go to Step 11
11Repair any problem with the coolant hoses.
Is the heater operating?–System OKGo to Step 12
12Check the surge tank cap.
Is the surge tank cap in good condition?–Go to Step 14Go to Step 13
13Repair or replace the surge tank cap as needed.
Is the heater operating?–System OKGo to Step 14
141. Set the A/C switch to OFF.
2. Set the temperature control to 32°C (90°F).
3. Set the blower motor speed to full high (all seg-
ments illuminated on the display).
4. Remove the surge tank cap.
5. Start the vehicle and run the engine at idle.
6. Watch for the flow of the coolant when the ther-
mostat opens.
Does the coolant flow?–Go to Step 16Go to Step 15

AUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7D – 9
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
151. Check for
S A faulty thermostat.
S A failed coolant pump impeller.
S A restriction in the cooling system.
2. Make repairs as needed.
Is the repair complete?–System OK–
16Check the temperature of the heater inlet and outlet
hoses by feel.
Is the heater inlet hose hot and the outlet hose
warm?–Go to Step 18Go to Step 17
17Back flush or replace the heater core.
Is the repair complete?–System OK–
18Check the vehicle for cold air leaks at the
S Dash.
S Heater cases.
S Vents.
Are any leaks found?–Go to Step 20Go to Step 19
19Repair any cold air leaks.
Is the repair complete?–System OK–
20Check the coolant temperature sensor using the
tests in ”Code 3 – Coolant Temperature Sensor Er-
ror.”
Is there a problem indicated in the sensor, the sensor
wiring, or the controller?–Go to Step 21Go to Step 22
21Repair or replace the sensor, the wiring, or the con-
troller as required.
Is the repair complete?–System OK–
22Check the in–car sensor using the tests in ”Code 1
– In–Car Sensor Error.”
Is there a problem indicated in the sensor, the sensor
wiring, or the controller?–Go to Step 23Go to Step 24
23Repair or replace the sensor, the wiring, or the con-
troller as required.
Is the repair complete?–System OK–
24Check the ambient air temperature sensor using the
tests in ”Code 2 – Ambient Air Temperature Sensor
Error.”
Is there a problem indicated in the sensor, the sensor
wiring, or the controller?–Go to Step 25Go to Step 26
25Repair or replace the sensor, the wiring, or the con-
troller as required.
Is the repair complete?–System OK–
26Check the sun sensor using the tests in ”Code 5 –
Sun Sensor Error.”
Is there a problem indicated in the sensor, the sensor
wiring, or the controller?–Go to Step 27Go to Step 28
27Repair or replace the sensor, the wiring, or the con-
troller as required.
Is the repair complete?–System OK–
28Replace the ATC controller.
Is the repair complete?–System OK–

AUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7D – 11
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
15Repair or replace the sensor, the wiring, or the con-
troller, as required.
Is the repair complete?–System OK–
16Check the sun sensor using the tests in ”Code 5 –
Sun Sensor Error.”
Is there a problem indicated in the sensor, the sensor
wiring, or the controller?–Go to Step 17Go to Step 18
17Repair or replace the sensor, the wiring, or the con-
troller as required.
Is the repair complete?–System OK–
18Perform the coolant temperature sensor test.
Is the coolant temperature sensor malfunctioning?–Go to Step 19Go to Step 20
19Replace the coolant temperature sensor.
Is the repair complete?–System OK–
20Replace the ATC controller.
Is the repair complete?–System OK–

7D – 22IAUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO V–121 BL4
CODE 3 – WATER SENSOR ERROR
This code will set if the output of the coolant sensor indicates a probable short circuit or an open in the sensor or the associ-
ated wiring harness, or a malfunction of the ATC controller.
Code 3 – Water Sensor Error
StepActionValue(s)YesNo
11. Disconnect the coolant temperature sensor
connector from the ATC harness.
2. Examine the wiring from the sensor to the con-
nector and examine the connector for any
signs of damage.
3. Measure the resistance between the coolant
temperature sensor connector terminals.
Is there any sign of damage in the wiring or the con-
nector, or is the resistance outside the specified val-
ue at 20 to 25°C (68 to 77°F)?2600–2100 ΩGo to Step 2Go to Step 3
2Repair the damaged wiring or the connector, or re-
place the coolant temperature sensor as required.
Is the repair complete?–System OK–
31. Turn the ignition to ON.
2. Measure the voltage between the two coolant
temperature sensor connector terminals on the
ATC harness.
Is the voltage equal to the specified value?< 4 vGo to Step 7Go to Step 4
4Check the terminals on the coolant temperature
sensor connector.
Is any problem found with the connector?–Go to Step 5Go to Step 6
5Repair the connector terminals or replace the cool-
ant temperature sensor or ATC controller as re-
quired.
Is the repair complete?–System OK–