Daewoo Nubira. Manual - part 187

7B – 16

I

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM

DAEWOO V–121 BL4

Step

No

Yes

Value(s)

Action

24

1.  Start the engine.
2.  Observe the low–side pressure gauge while

running the engine between 3,000 and 3,800
rpm.

Does the low–side pressure rise rapidly?

Go to Step 32

Go to Step 25

25

1.  Recover the A/C system refrigerant.
2.  Replace the A/C compressor.
3.  Evacuate and recharge the A/C system.

Is the compressor functioning normally?

Go to Step 13

26

Check the low–side pressure.
Is the low–side pressure within the specified value?

172–241 kPa

(27–38 psi)

Go to Step 27

Go to Step 32

27

Feel the high–side pipe leading up to the expansion
valve connecting block.
Is the pipe cold before the connecting block?

Go to Step 28

Go to Step 29

28

1.  Check for a restriction in the high–side pipe

before the expansion valve.

2.  Repair or replace the high–side pipe.

Is the repair complete?

Go toStep 13

29

Add the specified amount of refrigerant to the A/C
system.
Does the cooling performance improve?

0.40 kg (14 oz)

Go to Step 30

Go to Step 31

30

1.  Check the A/C system for leaks.
2.  Repair any refrigerant leaks, as needed.
3.  Evacuate and recharge the A/C system.
4.  Check the A/C system for leaks.

Is the system free from leaks?

Go to Step 13

31

1.  Recover the refrigerant.
2.  Check the expansion valve for obstructions.
3.  Repair or replace the expansion valve, as re-

quired.

4.  Evacuate and recharge the system.
5.  Check the A/C system for leaks.

Is the system free from leaks?

Go to Step 13

32

1.  Run the engine for 5 minutes at 2,000 rpm.
2.  Set the A/C controls to the following positions:

S

  The A/C to ON.

S

  The fresh air control switch to recirculate

(indicator lamp ON).

S

  The blower motor to 1.

S

  The temperature control knob to full cold.

3.  Close all of the vehicle’s windows and doors.
4.  Open the vehicle hood.

Is the low–side pressure within the specified value?

172–241 kPa

(25–35 psi)

Go to Step 13

Go to Step 33

33

1.  Recover the A/C system refrigerant.
2.  Replace the A/C compressor control valve.
3.  Evacuate and recharge the A/C system.
4.  Check the A/C system for leaks.

Is the system free from leaks?

Go to Step 13

 

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM  7B – 17

DAEWOO V–121 BL4

SYMPTOM DIAGNOSIS

PRESSURE TEST CHART (R–134a SYSTEM)

TEST RESULTS

RELATED SYMPTOMS

PROBABLE CAUSE

REMEDY

Discharge pressure
abnormally high

After stopping the compres-
sor, the pressure drops
about 299 kPa (28 psi)
quickly, then falls gradually.

There is air in the system.

Recover, evacuate and re-
charge the system with the
specified amount of refrig-
erant.

The condenser is exces-
sively hot.

There is excessive refrigerant in
the system.

Recover, evacuate and re-
charge the system with the
specified amount of refrig-
erant.

There is reduced or no air-
flow through the condenser.

The condenser or the radiator fins
are clogged.

Clean the condenser or the
radiator fins.

The condenser or the radia-
tor fan is not working prop-
erly.

S

  Check the voltage and the

fan rpm.

S

  Check the fan direction.

The line to the condenser is
excessively hot.

Restricted flow of refrigerant in
the system

Locate and repair the re-
striction.

Discharge pressure
abnormally low

The condenser is not hot.

Insufficient refrigerant in the sys-
tem.

S

  Check the system for a

leak.

S

  Charge the system.

The high and low pressures
are balanced soon after
stopping the compressor.
Low side pressure is higher
than normal.

Faulty compressor pressure relief
valve.

Repair or replace the com-
pressor.

Faulty compressor seal.

The outlet of the expansion
valve is not frosted, low
pressure gauge indicates
vacuum.

Faulty expansion valve.

Replace the expansion
valve.

Moisture in the system.

Recover, evacuate, and recharge
the system.

Suction pressure ab-
normally low

The condenser is not hot.

Insufficient refrigerant in the sys-
tem.

Repair the leaks. Recover,
evacuate, and recharge the
system.

The expansion valve is not
frosted and the low pres-
sure line is not cold. Low
pressure gauge indicates a
vacuum.

Frozen expansion valve.

Replace the expansion
valve.

Faulty expansion valve.

The discharge temperature
is low and the airflow from
the vents is restricted.

The evaporator is frozen.

Clear the restricted evapo-
rator case drain.

The expansion valve is
frosted.

The expansion valve is clogged.

Clean or replace the expan-
sion valve.

The receiver/drier outlet is
cool and the inlet is warm.

The receiver/drier is clogged.

Replace the receiver/drier.

7B – 18

I

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM

DAEWOO V–121 BL4

TEST RESULTS

REMEDY

PROBABLE CAUSE

RELATED SYMPTOMS

Suction pressure ab-
normally high

The low pressure hose and
check joint are cooler than
the temperature around the
evaporator.

The expansion valve is opened
too long.

Replace the expansion
valve.

A capillary tube is loose.

The suction pressure is low-
ered when the condenser is
cooled by water.

There is excessive refrigerant in
the system.

Recover, evacuate, and re-
charge the system.

The high and low pressures
are equalized as soon as
the compressor is stopped
and both gauges fluctuate
while the compressor is
running.

A gasket is faulty.

Repair or replace the com-
pressor.

The high pressure valve is
faulty.

Foreign particles are stuck
in the high pressure valve.

Suction and dis-
charge pressure ab-
normally high charge

There is reduced airflow
through the condenser.

The condenser or the radiator fins
are clogged.

Clean the condenser and
the radiator.

charge pressure ab-
normally high charge

The radiator cooling fans
are not working properly.

S

  Check the voltage and the ra-

diator cooling fan rpm.

S

  Check the fan direction.

The condenser is exces-
sively hot.

There is excessive refrigerant in
the system.

Recover, evacuate, and re-
charge the system.

Suction and dis-
charge pressure ab-
normally low

The low pressure hose and
themetal end areas are
cooler than the evaporator.

There is a clogged or kinked low
pressure hose.

Repair or replace the low
pressure hose.

The temperature around
the expansion valve is low
compared to that around
the receiver/drier.

The high pressure line is clogged.

Repair or replace the high
pressure line.

Refrigerant leaks

The compressor clutch is
dirty.

The compressor shaft seal is
leaking.

Repair or replace the com-
pressor.

The compressor bolts are
dirty.

There is leaking around a com-
pressor housing bolt.

Tighten the bolt(s) or re-
place the compressor.

The compressor gasket is
wet with oil.

The compressor gasket is leak-
ing.

Repair or replace the com-
pressor.

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM  7B – 19

DAEWOO V–121 BL4

LOW AND HIGH SIDE PRESSURE RELATIONSHIP CHART