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Great Wall service chassis and body Manual - part 91

AC-8

Air-Conditioning System

System Component

system component

liquid tank

compressor

condenser

HP hose

LP hose

Tightening moment for air-conditioning pipeline

Open-wrench spanner (mm)

Tightening moment(N

Threaded

joint of

com-

pressor

Threaded

joint

Pressing

plate bolt

Threaded head (mm)

Open-wrench spanner (mm)

Tightening moment(N

Air-conditioning pipe-line

Tightening moment(N

LP hose interface

HP hose interface

1.5

Dr SF

SL SK SY SJ

25~30

30~35

8~12

21~25

25~30

30~35

HP hose interface

evaporator

AC-9

Air-conditioning System - General introduction

General introduction

Refrigeration cycle

The refrigerant at the lower pressure side is condensed by the

compressor into the HT and HP gaseous refrigerant.

These gaseous refrigerant flows into the condenser, where it is

turned into liquid refrigerant.

Those liquid refrigerant flows into the liquid tank, where the

liquid refrigerant is stored and filtered so as to satisfy the

requirement of evaporator.

diaschage vent

indraft vent

compressor
curent direction

evaporator

heat

expansionvalve

liquid tank

The liquid refrigerant is throttled by the expansion valve to reduce the pressure, so that the liquid refrigerant is turned

into the LT and LP mixture of liquid and gaseous refrigerant.

The cold and fog-like refrigerant flows into the evaporator, where it is vaporized with the given heat, which is

absorbed from the hot air flow by the evaporator core. All liquid refrigerants are turned into the gaseous refrigerant

in the evaporator, and only the heated gaseous refrigerant is absorbed into the compressor. Then repeat the above-

mentioned cycling approach.

The refrigerant released from

the evaporator expands and

inflows through the evapora-

tor pipe. During this process,

the refrigerant absorbs the

heat in the air around the ra-

diating rib and pipe and

vaporizes, so that the tem-

perature inside the vehicle

reduces gradually.

The condenser allows the heated gas-

eous refrigerant to release heat to the

cooling air of engine, therefore, the gas-

eous refrigerant is cooled and turned

into liquid state again.

The expansion valve is used

to measure the gaseous re-

frigerant entered into evapo-

rator core, which reduces the

pressure and temperature of

refrigerant gradually.

The liquid tank is used to exhaust

the water in system and to filter

the dust and dunghill. It serves as

the store to store the redundant

refrigerant.

The compressor absorbs the
gaseous refrigerant emitted
from the evaporator and com-
presses it. In doing so, the tem-
perature and pressure of gas-
eous refrigerant increases
rapidly.

AC-10

Air-conditioning System - Troubleshooting

Troubleshooting

Trouble

Reparation approaches

Page

Lack of cold air

Non-pull-in performance of electromagnetic clutch:

(a)

Break of ignition switch and fuse;

(b)

Trouble of electromagnetic clutch;

(c)

Trouble of A/C switch;

(d)

Wiring or grounding trouble;

(e)

Lack of refrigerant; and

(f)

Trouble of pressure switch.

Abnormal operation of compressor:

(a)

Looseness or break of driving belt;

(b)

Compressor trouble;

Expansion valve trouble;

Systematic leakage;

Liquid tank fusible plug melting or filtering

screen blocking;

Non-work of air blower:

(a)

Failure of A/C switch;

(b)

Failure of air blower motor, and

(c)

Wiring failure.

Change the fuse and check to see whether

there is short circuit;

Check the electromagnetic clutch;

Check the A/C switch;

Repair it as requirement;

Check the refrigerant pressure;

Check the pressure switch;

Adjust or change the driving belt;

Check the compressor;

Check the expansion valve;

Conduct lubricating test for the system

Check the liquid tank;

Check the A/C switch;

Check the air blower motor;

Conduct reparation as requirement.

Inconsecutive

cold air

Electromagnetic valve slip

Failure of expansion valve;

Wiring or connecting failure;

Over water content in system

Check the electromagnetic clutch;

Check the expansion valve;

Make reparation as requirement.

Reclaim the water first, then exhaust the

system to vacuum and inflate in the refrigerant.

Cold air occurs in

high-speed condition

Blocking of radiating face of condenser;

Driving belt slip;

Compressor failure;

Insufficient or redundant refrigerant;

Air existing in system

Check and wash the condenser

Check and change the driving belt;

Check the compressor;

Check the refrigerant quantity;

Vacuumize the system and inflate

the refrigerant;

Insufficient

cold air

Condenser blocking;

Driving belt slip;

Electromagnetic clutch failure;

Compressor failure;

Expansion valve failure;

Insufficient or redundant refrigerant;

Air existing in system;

Redundant compressor lubricant;

Liquid tank block

Check the condenser;

Check and change the driving belt;

Check the electromagnetic clutch;

Check the compressor;

Check the expansion valve;

Check the refrigerant quantity;

Reclaim the air, then vacuumize the sys-

tem and inflate the refrigerant;

Check the compressor lubricant quantity;

Check the liquid tank

Evaporator blocking or frosting

Air leakage in cooling device or air

pipeline;

Air inlet blocking;

Air blower motor failure;

Clean the evaporator radiating rib

or filter;

Make reparation as requirement

Change the air blower motor.

Page AC-4 to 7

Page AC-12

Page AC-4 to 7

Page AC-11

Page AC-13

Page AC-12

Page AC-16

Page AC-14

Page AC-4 to 7

Page AC-12

Page AC-16

Page AC-4 to 7

Page AC-15

Page AC-12

Page AC-16

Page AC-11

Page AC-14

Page AC-18

Page AC-20

Possible causes

Page AC-15

Page AC-13

Page AC-12

Page AC-11

Under-speed cold air

AC-11

Air-Conditioning System

Inspection On Refrigerant Quantity

Inspection on Refrigerant Quantity

Run the engine at the speed of 1500 r/m or so (the

atmospheric temperature should be above 35

);

Start the air-conditioner in the max cold air status for

several minutes;

Check the refrigerant quantity.

Watch the observation window on liquid tank.

Dr SF

SL SK SY SJ

liquid tank

observation window

No.

Symptoms

Refrigerant quantity

Repairing approaches

Air bubble occurs in the observa-
tion window

No air bubble in observation win-
dow

No temperature difference between
the inlet and outlet of compressor

Obvious temperature difference be-

tween the inlet and outlet of compressor.

Observation window is in clear status

once the air-conditioner is turned off

There is refrigerant foam on observa-

tion window after the air-conditioner

is turned off, then the observation

window becomes clear.

Insufficient

No, normal or redundant

No, or almost no

Normal or redundant

Redundant

Normal

Check to see whether there is leakage with the

gas leakage detector

Refers 3 and 4.

Vacuumize the system and inflate the

refrigerant, then check to see whether there is

leakage with the gas leakage detector.

Refer 5 and 6

Exhaust the redundant refrigerant until the speci-

fied quantity is satisfied.

Content .. 89 90 91 92 ..