5A2 – 72IAISIN AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0748
PRESSURE CONTROL SOLENOID (PCS) ELECTRICAL
Conditions for Setting the DTC
S TCM detects that the feed back voltage is greater
than 4.9 volts and detects the detection 500 milli-
seconds continuously.(When the PCS circuit is
short to battery).
S TCM detects that the feed back voltage is less than
70.mV for 70 milliseconds and detects the 12.5
seconds continuously.(When the PCS circuit is
short to ground or open).
Action Taken When the DTC Sets
S TCM will request the illumination of MIL and store
DTC when TCM detects a failure on the first ignition
cycle.
S No lockup control
S No engine torque reduction control
S No engagement pressure control
S No 4th gearS No self–learning control
S After failure decision : emergency mode
Conditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
S TCM detects the feed back voltage is between
70mV and 4.9 v for 12.5 seconds continuously.
Cause of Failure
S Wiring harness or connector between Pressure
Control Solenoid (PCS) and TCM
S PCS
S TCM
AISIN AUTOMATIC TRANSAXLE 5A2 – 77
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0753
SHIFT SOLENOID 1 (SS1) ELECTRICAL
Conditions for Setting the DTC
S TCM detects that the ON signal of the Shift Sole-
noid 1 (SS1) monitor during 0.5 seconds when SS1
driver outputs the OFF signal.(When the SS1 circuit
is open or short to battery).
S TCM detects that the OFF signal of the Shift Sole-
noid 1 (SS1) monitor during 0.3 seconds when SS1
driver outputs the ON signal.(When the SS1 circuit
is short to ground).
S The above detection 2 times at shifting continuous-
ly.
Action Taken When the DTC Sets
S TCM will request the illumination of MIL and store
DTC when TCM detects a failure on the first ignition
cycle.
S No lockup control
S No engine torque reduction control
S No engagement pressure control
S No timing solenoid control for N–D
S No self–learning control
S After failure decision : emergency modeTCM Shifting Pattern (Range : D)
Normal
SS1 FAIL
GearSS1SS2GearSS1SS2
1 stONON3 rdFAILOFF
2 ndONOFF3 rdFAILOFF
3 rdOFFOFF3 rdFAILOFF
4 thOFFON4 thFAILON
Conditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
S TCM detects the ON signal of the SS1 monitor dur-
ing 160 ms when SS1 driver outputs the ON signal
and TCM detects the OFF signal of the SS1 moni-
tor during 160 ms when SS1 driver outputs the
OFF signal.
5A2 – 82IAISIN AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0758
SHIFT SOLENOID 2 (SS2) ELECTRICAL
Conditions for Setting the DTC
S TCM detects that the ON signal of the Shift Sole-
noid 2 (SS2) monitor during 0.5 seconds when SS2
driver outputs the OFF signal.(When the SS2 circuit
is open or short to battery).
S TCM detects that the OFF signal of the Shift Sole-
noid 2 (SS2) monitor during 0.3 seconds when SS2
driver outputs the ON signal.(When the SS2 circuit
is short to ground).
S The above detection 2 times at shifting continuous-
ly.
Action Taken When the DTC Sets
S TCM will request the illumination of MIL and store
DTC when TCM detects a failure on the first ignition
cycle.
S No lockup control
S No engine torque reduction control
S No engagement pressure control
S No timing solenoid control for N–D
S No self–learning control
S After failure decision : emergency modeTCM Shifting Pattern (Range : D)
Normal
SS2 FAIL
GearSS1SS2GearSS1SS2
1 stONON2 ndONFAIL
2 ndONOFF2 ndONFAIL
3 rdOFFOFF3 rdOFFFAIL
4 thOFFON3 rdOFFFAIL
Conditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
S TCM detects the ON signal of the SS2 monitor dur-
ing 160 ms when SS2 driver outputs the ON signal
and TCM detects the OFF signal of the SS2 moni-
tor during 160 ms when SS2 driver outputs the
OFF signal.
AISIN AUTOMATIC TRANSAXLE 5A2 – 85
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0785
TIMING SOLENOID (ST) ELECTRICAL
Conditions for Setting the DTC
S TCM detects that the ON signal of the Timing Sole-
noid (ST) monitor during 0.5 seconds when ST driv-
er outputs the OFF signal.(When the ST circuit is
open or short to battery).
S TCM detects that the OFF signal of the Timing So-
lenoid (ST) monitor during 0.1 seconds when ST
driver outputs the ON signal.(When the ST circuit is
short to ground).
S The above detection 3 times at shifting continuous-
ly.
Action Taken When the DTC Sets
S TCM will request the illumination of MIL and store
DTC when TCM detects a failure on the first ignition
cycle.
S After failure decision : emergency modeConditions for Clearing the DTC
S The TCM turns off the MIL when no further failures
detected for three consecutive ignition cycles.
S The scan tool can clear the DTC from the TCM his-
tory.
S The TCM clears the DTC from the TCM history
memory after forty consecutive warm up cycles
without fault.
S TCM detects the ON signal of the ST monitor dur-
ing 100 ms when ST driver outputs the ON signal
and TCM detects the OFF signal of the ST monitor
during 160 ms when ST driver outputs the OFF sig-
nal.
Cause of Failure
S Wiring harness or connector between Timing Sole-
noid (ST) and TCM
S ST
S TCM
MANUAL CONTROL HEATING, VENTILATION AND AIR CONDITIONING SYSTEM 7B – 11
DAEWOO V–121 BL4
LEAK TESTING REFRIGERANT
SYSTEM
Test for leaks whenever you suspect a refrigerant leak in
the system. You should also test for leaks whenever you
perform a service operation which results in disturbing the
lines or the connections. Leaks are commonly found at the
refrigerant fittings or at the connections. Leaks are com-
monly caused by the following problems:
S Improper torque.
S Damaged O–ring seals.
S Dirt or lint on the O–ring seals.
Liquid Leak Detectors
Use a liquid leak detector solution on locations such as fit-
tings. Apply the solution to the area in question with the
swab that is supplied with the solution. Look for bubbles
to appear. This will indicate the existence and the location
of any leak.
For areas where this is not practical, such as sections of
the evaporator and the condenser, an electronic leak de-
tector is more useful.
Electronic Leak Detectors
Follow the manufacturer’s instructions for calibration, op-
eration, and maintenance of an electronic leak detector.
Battery condition is especially important to the accuracy
of a portable model. Set the detector to R–134a before be-
ginning the test.
Notice : Electronic leak detectors are sensitive to wind-
shield washing solutions, solvents and cleaners, and cer-
tain vehicle adhesives. Surfaces must be clean to prevent
false readings. Make sure that all surfaces are dry to pre-
vent damage to the detector.
General Testing Instructions
1. Follow the entire path of the refrigerant system.
2. Completely circle each joint at 25 to 50 mm (1 to 2
inches) per second.
3. Hold the probe tip within 6 mm (1/4 inch) of the sur-
face.4. Do not block the air intake.
5. The audible tone changes from 1 to 2 clicks per
second into a solid alarm if there is a leak. Adjust
the balance control to maintain 1 to 2 clicks per
second.
6. Test all of the following areas, even after one leak
has been confirmed:
S Evaporator inlet and outlet.
S Receiver–drier inlet and outlet.
S Condenser inlet and outlet.
S Brazed and welded areas.
S Damaged areas.
S Hose couplings.
S Compressor rear head.
S All fittings and joints.
Testing Service Ports/Access Valves
The sealing caps provide protection for the service ports.
Make sure that these caps are not missing or loose. Al-
ways use the correct cap for each port.
Testing the Evaporator Core
Leaks in the evaporator core are difficult to find. Test the
evaporator core using the following procedure:
1. Run the blower fan at the maximum speed setting
for at least 15 minutes.
2. Turn the blower OFF.
3. Wait for 10 minutes.
4. Remove the blower motor resistor. Refer to Section
7A, Heating and Ventilation System.
5. Insert the leak detector probe as close as possible
to the evaporator core. The detector will indicate a
leak with a solid alarm.
6. Use a flashlight to search for refrigerant oil on the
core surface.
Testing the Compressor Shaft Seal
1. Blow shop air behind and in front of the compressor
clutch/pulley for at least 15 seconds.
2. Wait 1 to 2 minutes.
3. Probe the area in front of the pulley. If the detector
emits a solid alarm, there is a leak.
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.
7B – 52IMANUAL CONTROL HEATING, VENTILATION AND AIR CONDITIONING SYSTEM
DAEWOO V–121 BL4
SYSTEM COMPONENTS–CONTROL
Controller
The operation of the A/C system is controlled by the
switches and the lever on the control head. The compres-
sor clutch and the blower are connected electrically to the
control head by a wiring harness. The blower circuit is
open in the OFF mode. Airflow is provided by the four
blower speeds available in the remaining modes. Cooled
and dehumidified air is available in the MAX, NORMAL,
BI–LEVEL, and DEFROST modes.
The temperature is controlled by the position of the tem-
perature knob on the control head. A cable connects this
knob to the temperature door, which controls the airflow
through the heater core. As the temperature knob is
moved through its range of travel, a sliding clip on the
cable at the temperature valve connection should assume
a position ensuring that the temperature door will seat in
both extreme positions. The temperature door position is
independent of the mode control switch. The temperature
door on some models is controlled electrically, eliminating
the need for the temperature cable.
The electric engine cooling fan on some vehicles is not
part of the A/C control system; however, the fan is opera-
tional any time the A/C control is in the MAX, NORMAL,
or BI–LEVEL modes. Some models provide for engine
cooling fan operation when the controller is in the DE-
FROST mode. This added feature is part of the A/C con-
troller function and is aimed at preventing excessive com-
pressor head temperatures. It also allows the A/C system
to function more efficiently. On some models, the engine
cooling fan will be turned off during road speed conditions
above 56 km/h (35 mph), when the airflow though the con-
denser coil is adequate for efficient cooling. The operation
of the cooling fan is controlled by the powertrain control
module (PCM), or the engine control module (ECM),
through the cooling fan relay.
Pressure Transducer
The pressure transducer incorporates the functions of the
high–pressure and the low–pressure cutout switches
along with the fan cycling switch. The pressure transducer
is located in the high–side liquid refrigerant line near the
right front strut tower and the air filter assembly.
Wide–Open Throttle (WOT) Compressor
Cutoff
During full throttle acceleration on vehicles equipped with
multi–port injection (MPI), the throttle position sensor
(TPS) sends a signal to the PCM or the ECM, which then
controls the compressor clutch.
A/C Time Delay Relay
This relay on some vehicles controls the current to the en-
tire A/C system and provides a short delay of A/C opera-
tion upon start–up.
V5 COMPRESSOR–GENERAL
DESCRIPTION
Different vehicles with V5 compressors may exhibit differ-
ences in mounting and installation, but overhaul proce-
dures are similar.
Before removing the compressor or performing on–ve-
hicle repairs, clean the compressor connections and the
outside of the compressor.
Important : After removing a compressor from the vehicle
for servicing, drain the oil by removing the oil drain plug.
Also drain the oil from the suction and the discharge ports
to insure complete draining. Measure the amount of oil
drained, and record that amount. Discard the used oil and
add the same amount of new polyalkaline glycol (PAG) re-
frigerant oil to the compressor.
The compressor has been removed from the vehicle un-
less otherwise indicated.
Clean tools and a clean work area are important for proper
servicing. Keep dirt and foreign material from getting on or
into the compressor parts. Parts that are to be reassem-
bled should be cleaned with trichloroethane, naphtha,
stoddard solvent, kerosene, or equivalent solvents. Dry
the cleaned parts with clean dry air. Use only lint–free
cloths to wipe the parts.
V5 COMPRESSOR–DESCRIPTION OF
OPERATION
The V5 is a variable displacement compressor that can
match the automotive air conditioning (A/C) demand un-
der all conditions without cycling. The basic compressor
mechanism is a variable angle wobble–plate with five ax-
ially oriented cylinders. The center of control of the com-
pressor displacement is a bellows–actuated control valve
located in the rear head of the compressor. The control
valve senses compressor suction pressure.
The wobble–plate angle and the compressor displace-
ment are controlled by the crankcase suction pressure dif-
ferential. When the A/C capacity demand is high, the suc-
tion pressure will be above the control point. The valve will
maintain a bleed from crankcase to suction. With no
crankcase suction pressure differential, the compressor
will have maximum displacement.
When the A/C capacity demand is lower and the suction
pressure reaches the control point, the valve will bleed dis-
charge gas into the crankcase and close off a passage
from the crankcase to the suction plenum. The angle of the
wobble–plate is controlled by a force balance on the five
pistons. A slight elevation of the crankcase suction pres-
sure differential creates total force on the pistons resulting
in a movement about the wobbleplate pivot pin that re-
duces the plate angle.
The compressor has a unique lubrication system. The
crankcase suction bleed is routed through the rotating
wobble–plate for lubrication of the wobble–plate bearing.
The rotation acts as an oil separator which removes some
AUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7D – 5
DAEWOO V–121 BL4
DIAGNOSIS
GENERAL A/C DIAGNOSTICS
Refer to Section 7B, Manual Control Heating, Ventilation,
and Air Conditioning System for details of the following
procedures:
S A/C Performance Test.
S Insufficient Cooling ”Quick Check” Procedure.
S Insufficient Cooling Diagnosis.S Leak Testing the Refrigerant System.
S Low– and High–Side Pressure Relationship Chart.
S Pressure Test Chart (R–134a System).
S Pressure–Temperature Relationship of R–134a.
S Testing the Refrigerant System.
V5 SYSTEM AIR CONDITIONING AND AUTOMATIC
TEMPERATURE CONTROL (ATC)
SELF–DIAGNOSTIC CIRCUIT CHECK
The Daewoo fully automatic temperature controller
(FATC) contains a self–diagnosis function to aid in finding
any problem with the system. To enter the diagnostic
mode, perform the following procedure:
1. Turn the ignition to ON.
2. Set the temperature control to 26°C (79°F).3. Within 3 seconds, push the AUTO and the OFF
switches simultaneously, more than three times.
4. Count the number of times the temperature indica-
tor screen blinks.
5. If there are no error codes set, the screen will not
blink. When the controller indicates an error code,
proceed to the table for that code.
6. Push the OFF switch to return the controller to its
normal functions.