Daewoo Nubira. Manual - part 186

7B – 12

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM

DAEWOO V–121 BL4

LEAK TESTING THEREFRIGERANT
SYSTEM

Test for leaks whenever a refrigerant leak in the system is
suspected. Also, test for leaks whenever a service opera-
tion which results in disturbing the lines or the connections
is performed. Leaks are commonly found at the refrigerant
fittings or at the connections. Leaks are commonly caused
by the following problems:

Improper

torque.

Damaged O–ring seals.

Dirt or lint on the O–ring seals.

Liquid Leak Detectors

Use a liquid leak detector solution on locations such as the
fittings. 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 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.

Important : Electronic leak detectors are sensitive to
windshield washing solutions, solvents and cleaners, and
certain vehicle adhesives.

Surfaces must be clean to prevent false readings. Make
sure that all surfaces are dry to prevent damage to the de-
tector.

General Testing Instructions

Follow the entire path of the refrigerant system.

Completely circle each joint at 25 to 50 mm (1 to 2
inches) per second.

Hold the probe tip within 6 mm (1/4 inch) of the sur-
face.

Do not block the air intake.

The audible tone changes from 1 to 2 clicks per second
into a solid alarm if there is a leak. Adjust the balance con-
trol to maintain 1 to 2 clicks per second.

Test all of the following areas, even after one leak has been
confirmed:

Evaporator inlet and outlet.

Receiver–drier inlet and outlet.

Condenser inlet and outlet.

Brazed and welded areas.

Damaged

areas.

Hose

couplings.

Compressor rear head.

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 speed setting 4 for at least 15

minutes.

2.  Turn the blower OFF.
3.  Wait for 10 minutes.
4.  Remove the blower motor resistor. Refer to”Blower

Resistor” in this section.

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 in 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 – 13

DAEWOO V–121 BL4

V5 SYSTEM AIR CONDITIONING DIAGNOSIS

INSUFFICIENT COOLING DIAGNOSIS

Test Description

The number(s) below refer to step(s) on the diagnostic
table.

13. See the first Important below.
32. See the second Important below.

Important : Perform this test under garage conditions with
the air temperature at 21–32

C (70–90

F), and no sun

load. Follow this test carefully for accurate results.

Important : Perform this test exactly as described to ob-
tain accurate results.

Insufficient Cooling Diagnosis

Step

Action

Value(s)

Yes

Record the customer’s complaint.
Can you verify the customer’s complaint?

Go to Step 2

System OK

1.  Check the A/C fuse.
2.  Check the blower fan operation.
3.  Check the engine cooling fan operation.
4.  Check the A/C compressor belt.
5.  Check the A/C condenser for restricted airflow.
6.  Check the clutch coil connection.
7.  Repair or replace any components as needed.
8.  Check the discharge air temperature with the

A/C ON.

Is the discharge air temperature normal?

At least 7

(12

F) below

ambient air

temperature

System OK

Go to Step 3

1. Turn the ignition to LOCK.
2. Connect the high– and the low–pressure

gauges.

Are both pressures within the specified value?

69–345 kPa

(10–50 psi)

Go to Step 4

Go to Step 5

1.  Check the A/C system for leaks.
2.  Repair any refrigerant leaks, as needed.
3.  Recover, evacuate, and recharge the A/C sys-

tem.

4. Observe the two pressure gauges.

Are both pressures above the specified value?

345 kPa (50

psi)

Go to Step 7

Observe the two pressure gauges.
Are both pressures below the specified value?

69 kPa (10 psi)

Go to Step 6

Go to Step 7

1.  Add 0.45 kg (1 pound) of refrigerant R–134a.
2.  Check the A/C system for leaks.
3.  Repair any refrigerant leaks, as needed.
4.  Recover, evacuate, and recharge the A/C sys-

tem.

5. Observe the two pressure gauges.

Are both pressures above the specified value?

345 kPa (50

psi)

Go to Step 7

1. Start the engine and allow it to run at idle.
2. Set the A/C controls to the following positions:

The A/C to ON.

The fresh air control switch to fresh air (in-

dicator lamp OFF).

The blower motor to 4.

The temperature control knob to full cold.

Does the A/C compressor clutch engage?

Go to Step 8

Go to Step 10

7B – 14

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM

DAEWOO V–121 BL4

Step

Yes

Value(s)

Action

1. Check for a knocking noise from the A/C com-

pressor.

2. Cycle the A/C compressor ON and OFF in or-

der to verify the source of the noise.

Do you hear a loud knocking noise?

Go to Step 9

Go to Step 13

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

Is the compressor running normally?

Go to Step 13

1. Turn the ignition to LOCK.
2. Disconnect the A/C compressor clutch coil con-

nector.

3. Connect a jumper wire from ground to one A/C

compressor clutch coil terminal.

4. Connect a fused jumper wire from the positive

battery terminal to the other A/C compressor
clutch coil terminal.

Does the A/C clutch engage?

Go to Step 11

Go to Step 12

Repair the electrical circuit to the A/C compressor
clutch coil.
Does the A/C clutch engage?

Go to Step 8

Replace the A/C compressor clutch coil.
Does the A/C clutch engage?

Go to Step 8

1. Close all of the vehicle’s windows and doors.
2. Set the A/C controls to the following positions:

The A/C to ON.

The fresh air control switch to fresh air.

The blower motor to 4.

The temperature control knob to full cold.

3. Start the engine and allow it to run at idle for 5

minutes.

4. Feel the evaporator inlet and outlet pipes.

Is there a noticeable difference in the temperature of
the evaporator inlet and outlet pipes?

Go to Step 15

Go to Step 14

1.  Turn the ignition to LOCK.
2.  Recover the A/C system refrigerant.
3.  Examine the high–pressure pipe for an ob-

struction.

4. Examine the expansion valve for an obstruction

or a malfunction.

5. Repair the obstruction or replace the expansion

valve, as needed.

6.  Evacuate and recharge the A/C system.
7.  Check the A/C system for leaks.
8.  Note the discharge air temperature with the

A/C ON.

Is the discharge temperature normal?

At least 7

(12

F) below

ambient air

temperature

Go to Step 15

Go to Step 13

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7B – 15

DAEWOO V–121 BL4

Step

Yes

Value(s)

Action

1. Record the high– and low–side pressures after

the A/C system has been operating for 5 min-
utes or more with the engine cooling fan ON.

2. Locate the intersection of the high– and low–

side pressures. Refer to ”Low– and High–Side
Pressure Relationship Chart” in this section.

Do the low– and high–side pressures intersect in the
white area of the chart?

System OK

Go to Step 16

Check the high– and low–side pressures.
Do the high– and low–side pressures intersect in the
gray area of the chart?

Go to Step 17

Go to Step 20

Feel the liquid pipe between the condenser and the
expansion valve.
Is the pipe cold?

Go to Step 18

Go toStep 19

1. Examine the condenser for any restriction of

the airflow.

2. Check the cooling fans for proper operation.
3. Remove the restriction or repair the fans, as

required.

Is the pipe temperature normal?

At least 7

(12

F) below

ambient air

temperature

Go to Step 13

1. Recover, evacuate, and recharge the A/C sys-

tem.

2. Check the A/C system for leaks.

Is the system free from leaks?

Go to Step 13

Observe the readings on the pressure gauges.
Are the A/C compressor high– and low–side pres-
sures within the specified value of each other?

207 kPa (30

psi)

Go to Step 21

Go to Step 26

1. Run the engine at 3,000 rpm.
2. Set the A/C controls to the following positions:

The A/C to ON.

The fresh air control switch to fresh air.

The blower motor to 4.

The temperature control knob to full cold.

3. Close all of the vehicle’s windows and doors.
4. Turn the A/C ON and OFF every 20 seconds

for 3 minutes.

Are the A/C compressor high– and low–side pres-
sures within the specified value of each other?

207 kPa (30

psi)

Go to Step 22

Go to Step 13

Observe the pressure rise on both gauges and the
temperatures of both the compressor suction pipe
and the discharge pipe.
Is the pressure rise on both gauges slow and the
suction pipe warm with the discharge pipe very hot?

Go to Step 25

Go to Step 23

1. Turn the ignition to LOCK.
2. Make sure the compressor clutch is disen-

gaged.

3. Attempt to turn the clutch driver (not the

pulley).

Can you turn the clutch driver freely by hand?

Go to Step 25

Go to Step 24

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