Service & Maintenance Manual

AC112 & CN268/328 Bus Air-Conditioning Units

CN268/328 & AC112

Content

Introduction Function Of An Air Conditioning System

Maintenance and Service

Maintenance Chart

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English Version

Attachment

P2 ~ P9

P10 ~ P14

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200-300

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1500r/min 10 15

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R134a

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Operation & Maintenance Manual

Introduction

This guide has been prepared for the operator of the air conditioning unit. It

contains basic instructions for the daily operation of the air conditioning unit as

well as safety information, maintenance and service, the maintenance chart and

the inspection chart.

Your air conditioning unit has been engineered to provide long, trouble-free

performance when it is properly operated and maintained. The maintenance and

service outlined in this guide will help to minimize over-the-road-problems. The

maintenance chart and inspection chart will also help to control operating costs,

increase the unit's working life, and improve performance.

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Operation & Maintenance Manual

Function Of An Air Conditioning System

See Attachment.

Refrigerant, in its gaseous state, is drawn from the evaporator into the compressor.

During compression, the refrigerant gas under goes both an increase in

temperature and pressure. The hot, high-pressured gas is discharged to the

condenser.

Through a combination of air movement decreasing the temperature in and

around the condenser coils, plus the increased pressure created by the

compressor, the gas is condensed. During this process, the heat is released by

the condenser coils and expelled by the condenser fans through air movement

across the cooling fins.

From the condenser, the liquid refrigerant is forced into the receiver-drier.

From the receiver-drier, the refrigerant flows via the high-pressure liquid line

through the sight glass to the expansion valve. The function of the expansion valve

is to control the amount of liquid refrigerant entering the evaporator coils so that

proper coolant vaporization occurs.

In order to ensure that the coolant is distributed evenly in the evaporator the

refrigerant is fed via a distributor and several capillary tubes into the evaporator

coils.

The last step in the cooling cycle is the evaporation of the low-pressure liquid

refrigerant with in the evaporator coils. Because the expansion valve allows only a

controlled amount of liquid refrigerant within the evaporator coils, the internal

pressure of the coils is reduced. This reduction in pressure causes the refrigerant

to become a gas and heat is absorbed in this progress.

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Operation & Maintenance Manual

Maintenance and Service

The efficient performance of the air conditioning units is dependent upon proper

maintenance and function-tests. A thorough visual inspection and function test by

the driver, before any performance, will avoid expensive repairs. Little faults are

often responsible for big repairs. Working reliability and life cycle of the air-

conditioning unit depend upon a regular maintenance chart.

If the air conditioning units are operated under extreme conditions (dust, snow...),

intervals have to be adjusted to the needs.

If the air conditioning units are not used for a long time, for example in winter, the

air conditioning units must be operated at least once a month, for a minimum of

30 minutes. This operation prevents gaskets drying out and bearings in the

compressor oxidizing. The compressor will be lubricated by its own oil pump only

when the ac-unit is in operation.

Kindly check unit covers are well closed by ensuring all locking bolts are properly

secured.

The air conditioning system is a closed circuit, that's why total cleanliness must be

the aim of the service engineer. Once a contaminant enters the system it will

remain there. The only intervention is to get it removed by a service engineer.

Contaminants usually react slowly. A system may start up initially and run perfectly:

a few months later it will be found to be badly damaged, perhaps beyond repairs.

The refrigerant circuit is pressurized. Uncontrolled refrigerant discharge can lead

to serious injuries. National regulations concerning the use and disposed of

refrigerant in air conditioning systems should be observed.

Air conditioning units with a separate diesel drive unit: For regular maintenance

work on the diesel engine, use maintenance chart in operating instructions for the

particular diesel engine. Separate operating instructions for the diesel engine are

supplied with the documentation of the air conditioning units.

Note:

During the run-in period some oil might get transported outside the compressor

producing there some oil drops. This doesn't mean that the shaft seal is leaking;

therefore there is no need to replace it. After the run-in period (about 200-300

working hours) the shaft seal will work normally. To operate the units during winter,

the inside temperature has to be higher than the cut off set point of the thermostat.

(Therefore the passenger compartment has to be heated up if necessary or switch

on the climate control center to permanent cooling.)

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Operation & Maintenance Manual

Maintenance Chart

Weekly maintenance

1.Clean air filter mats at return air intake and at evaporators. Take out filter mats,

flush in hand-warm water using fine detergent, shake and allow to dry. Replace

damaged filter mats.

2.Check functions of evaporator blowers and condenser fans (check rotation

direction).

3.Check v-belt tension at compressor drive (see instructions of vehicle

manufacturer). Adjust if necessary. Renew damaged v-belts and use matched

sets.

4.Check refrigerant filling at sight glass. The units have to run for approx. 10-15

minutes at a minimum of 1500 rpm. The sight glass has to appear clear and free

of bubbles.

Monthly maintenance

These maintenance procedures should executed only by trained and skilled

personnel.

1.Check condenser, clean if necessary. Straighten bend fins. To clean dusty

condenser use compressed air against the usual air flow direction. To remove dirt

and foreign objects, steam cleaning and pressure washing are the standard

methods for cleaning. Strong caustic soaps and acid methods should be avoided.

2.Check drains tubes for dirt or restrictions.

3.Check refrigerant hoses, liquid lines and wires for leaks, loose connections and

wear.

4.Avoid contact with hot parts and sharp edges. Protect electric connections from

corrosion.

5.Check all fixing screws, mountings and bracket for tightness and cracks. Tighten

loose bolts, replace worn parts and lubricate v-belts tension pulleys and shafts.

Maintenance once a year

These maintenance procedure should be done latest every 100 000 km.

This inspection must be done by a refrigeration specialist!

1.Check refrigeration system for leak.

2.Check refrigeration lines and connections for tightness, leaks and mountings.

3.Renew contaminated refrigerant oil.

4.Renew filter drier.

5.Check function of high-and low-pressure switch.

6.Check high pressure cycling switch (if installed).

7.Check compressor for leaks, capacity and mounting.

8.Check oil level.

9.Check function of capacity regulator (if installed).

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10.Check function and bearing of electro-magnetic-clutch. Ensure correct seat of

clutch of compressor shaft.

11.Check condition of air conditioning housing, seals and locks.

12.Check function of A/C-unit.

13.Cooling: Set climate control center to permanent cooling.

14.Heating: Set climate control center to permanent heating.

15.Check ventilation.

16.Check circulation air.

17.Check function and condition of electric system.

18.Check function of thermostat and operating control.

19.Check function of fresh air flaps.

20.Replace pollen filter (if installed).

21.Check v-belts for adjustment, tension and wear.

22.Check receiver. Replace if corroded.

Operation & Maintenance Manual

Maintenance Chart

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CN268/328 & AC112

Attachment

CN268/328CN268/328 Refrigeration System Diagram

1 ELECTRIC VALVE

2 LIQUID INDICATOR

3 VALVE, EXPANSION

4 6 EVAPORATOR FAN(6pcs)

5 Filter DRIER

6 CN268 4 CN328 5

CONDENSER FAN(CN268: 4pcs, CN328: 5pcs)

7 RECEIVER

8 Service VALVE

9 PIPE

10 COMPRESSOR

CN268/328 & AC112

Attachment

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AC112AC112 Refrigeration System Diagram

1 ELECTRIC VALVE

2 LIQUID INDICATOR

3 VALVE, EXPANSION

4 4 EVAPORATOR FAN(4pcs)

5 Filter DRIER

6 4 CONDENSER FAN(4pcs)

7 RECEIVER

8 Service VALVE

9 PIPE

10 COMPRESSOR

1235 201821 86-21-59166868 86-21-59165013

Headquarter: No.1235 Ye Cheng Rd. Jiading District, Shanghai, 201821, China Tel: 86-21-59166868 Fax: 86-21-59165013

60 200434 86-21-65285295 86-21-65923827

Service Centre: No.60 Guang Yue Rd. Shanghai, 200434, China Tel: 86-21-65285295 Fax: 86-21-65923827

77-66884-00 Rev. -

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