1、汽车实用英语Unit 8 Air Conditioning System ServiceUpon completion of this unit,you should be able to:Overall Objectives Learn key terms about air conditioning system in this unit.Understand the process of inspection and repair of air conditioning system.Use maintenance manual to deal with the practical pr
2、oblems.Task 8.1 Air Conditioning System Overview 空调系统概述Task 8.2 Troubleshooting Air Conditioning System 空调系统故障检测Task 8.3 Pressure detection and Refrigerant replacement 压力检测与制冷剂更换Task 8.4 Detection of sensors 传感器的检测Task 8.5 Compressor and magnetic clutch inspection 压缩机和电磁离合器的检修Tasks Introduction When
3、 the hot summer comes,it is very bad that automobile air conditioning doesnt work well.It is necessary to look up the repair manual and find a way to troubleshoot the faults of AC.The following tasks(e.g.pressure detection and refrigerant replacement,detection of sensor,maintenance of air conditioni
4、ng system,etc.)are the common items in air conditioning system servicing to avoid major damage or keep the air conditioning system running normally.Task Description Task 8.1 Air Conditioning System OverviewLearning Preparation air conditioning 空调Airflow 气流Defroster 除雾器Amplifier 放大器blower motor 电风扇Em
5、it 发射Compressor 压缩机Load 负荷Pulley 滑轮solenoid valve 电磁阀 Key terms:Step 1 A maintenance case is provided;Step 2 Learn the structure of air conditioning system via a maintenance manual;Step 3 Require students to grasp the key terms in this task;Step 4 Try to describe the structure of air conditioning sy
6、stem;Step 5 Students read relative material;Step 6 Assessment.Plan and Implement ()1.Refrigerant must be handled in an enclosed area or near an open flame.()2.When handling refrigerant,we neednt wear protection.()3.Dont apply hair spray or stick any foreign matter into the Plasmacluster ion outlet.(
7、)4.Do not operate the compressor with no refrigerant.()5.While using the battery during inspection,do not bring the positive and negative tester probes too close to each other as a short circuit may occur.Assessment and Feedback True or False()6.If the check is performed in a dark place,DTC 21 or 24
8、 may be displayed even though the system is normal.()7.A vacuum pump should be used to perform vacuum purging.()8.Please turn the A/C on before charging with Origerant.()9.Keep the A/C switch on for at least 2 minutes to warm up the compressor.()10.If a gas leak is not detected from the drain hose,r
9、emove the blower motor control from the cooling unit.The purpose of the cars air conditioning system is simple.Its there to keep the car cool during a trip in hot or humid weather.The air conditioner makes the car more comfortable for the driver and passengers alike.Many of todays cars allow the tem
10、perature to be set to a certain degree and the air conditioner or heater will adjust the air until the desired temperature is reached.The only drawback to air conditioning is its affect on the gas mileage of the car.Studies are being done to determine how air conditioning affects a cars gas mileage
11、as compared to how other things,such as rolling down the windows,affect the gas mileage.8.1.1 How Does Air Conditioning Work?The air conditioner works much like the refrigerator used in your home.It has five basic parts:receiver,expansion valve,evaporator,compressor and condenser.(Fig.8.1.1)As the c
12、ompressor raises the pressure of the refrigerant,it also heats it.The hot refrigerant is then pumped into the condenser,where it is cooled off by giving off heat to air passing over the condenser fins.As the refrigerant cools,it condenses into liquid.Still under high pressure,the refrigerant passes
13、into the receiver.The receiver acts as a storage tank to send refrigerant to the expansion valve at all times.From the receiver,the high-pressure liquid refrigerant passed to the expansion valve.The expansion valve controls the flow of refrigerant into the evaporator,where a low pressure is maintain
14、ed by the suction side of the compressor.As it enters the evaporator,the refrigerant begins8.1.2 Air Conditioning Systemto boil by absorbing the heat from the air passing over theevaporator core.Having given up its heat to boil the refrigerant,the air is cooled and passes into the passenger compartm
15、ent.The refrigerant continues to boil in the evaporator until all the liquid has been vaporized.From the evaporator,the refrigerant flows back to the compressor to repeat the cycle.Fig.8.1.1 Air Conditioner1-blower;2-evaporator;3-expansion valve;4-compressor;5-condenser;6-fan;7-drierPractice Mainten
16、ance Manual Reading Air Conditioning SystemPractice Maintenance Manual Reading 1.Mode Position and Damper Operation(for Automatic A/C)Practice Maintenance Manual Reading Functions of Main Dampers:Practice Maintenance Manual Reading 2.Air Outlets and Airflow Volume(a)Air Outlets and Airflow VolumePra
17、ctice Maintenance Manual Reading Practice Maintenance Manual Reading The size of the circle indicates the proportion of airflow volume.1:Greater airflow volume at the upper area2:Greater airflow volume at the lower area3:Greater airflow volume at the front4:Greater airflow volume at the rear5:Greate
18、r airflow volume at the defroster6:Only for models with automatic air conditioning.3.Plasmacluster Ion Generator Control(a)General:(1)A Plasmacluster ion generator is provided inside the air duct of the side register on the driver seat side to improve the air quality and comfort in the cabin.(2)This
19、 generator is controlled by the A/C amplifier and operates in conjunction with the blower motor.Practice Maintenance Manual Reading NOTICE:The Plasmacluster ion generator uses a high voltage,which is hazardous.Therefore,if the Plasmacluster ion generator requires repairs,be sure to have them done at
20、 a TOYOTA dealer.Do not apply any type of spray(such as a cleaning solvent or hair spray)or stick any foreign matter into the Plasmacluster ion outlet,as this could cause improper operation or a malfunction.After use,dust may accumulate around the side register on the driver seat side.When this occu
21、rs,press the OFF switch on the heater control panel to stop the blower motor before cleaning the area.It is normal for the Plasmacluster Ion generator to emit a slight sound during operation.This sound is created when electrons collide with the electrode while Plasmacluster Ions are being generated.
22、Practice Maintenance Manual Reading HINT PlasmaclusterTM,plasmacluster,and plasmacluster ions are trademarks of the SHARP Corporation.(b)Operation:(1)The Plasmacluster ion generator produces positive and negative ions from the water molecules(H2O)and oxygen molecules(O2)in the air,and emits them int
23、o the air.Theseions reduce airborne germs.4.Blower Motor The blower motor has a built-in blower controller,and is controlled with duty control from the A/C amplifier.5.A/C Compressor (a)GeneralPractice Maintenance Manual Reading(1)The A/C compressor is a continuously variable capacity type in which
24、its capacity can be varied in accordance with the cooling load of the air conditioning.(2)This compressor consists of the A/C pulley,shaft,lug plate,swash plate,piston,shoe,crank chamber,cylinder,and solenoid valve.(3)The A/C pulley with built-in magnetic clutch and the lock sensor that detects whet
25、her the magnetic clutch is locked are installed on models with the 2GR-FE.(4)The DL(Damper Limiter)type A/C pulley is installed on models with the 2AZ-FE.(5)A solenoid valve that adjusts the suction pressure so that the compressor capacity can be controlled as desired is provided.Practice Maintenanc
26、e Manual Reading (6)The internal valve is provided on models with 2AZ-FE to improve the A/C compressor durability under the high speed and large thermal load conditions.The internal valve is integrated into the solenoid valve.(b)Solenoid Valve Operation (1)The crank chamber is connected to the disch
27、arge passage.A solenoid valve is provided between the discharge passage(LO pressure)and the discharge passage(HI pressure).(2)The solenoid valve operates under duty cycle control in accordance with the signals from A/C amplifier.(3)When the solenoid valve closes(solenoid coil is energized),a differe
28、nce in pressure is created and the pressure in the crank chamber decreases.Then,the pressure that isapplied to the right side of the piston becomes greater than thePractice Maintenance Manual Reading pressure that is applied to the left side of the piston.This compresses the spring and tilts the swa
29、sh plate.As a result,the piston stroke increases and the discharge capacity increases.(4)When the solenoid valve opens(solenoid coil is not energized),the difference in pressure disappears.Then,the pressure that is applied to the left side of the piston becomesthe same as the pressure that is applie
30、d to the right side of the piston.Thus,the spring elongates and eliminates the tilt of the swash plate.As a result,there is no piston stroke and the discharge capacity is reduced.(c)Internal Valve Operation(for 2AZ-FE)(1)The internal valve operates when the A/C compressor speed has increased rapidly
31、,the A/C compressor speed is high,or when thermal load has suddenly changed.As a result,Practice Maintenance Manual Reading the A/C compressor capacity is reduced,increasing the durability of the A/C compressor.(d)DL type A/C Pulley(for 2AZ-FE)(1)This pulley contains a damper to absorb the torque fl
32、uctuations of the engine and a limiter mechanism to protect the drive belt in case the compressor locks.In the event that the compressor locks,the limiter mechanism causes the spoke portion of the pulley to break,thus separating the pulley from the compressor.Practice Maintenance Manual Reading 6.Re
33、frigerant line components(for TMC made 2AZ-FE)Task 8.2 Troubleshooting Air Conditioning SystemLearning Preparation Troubleshoot 故障检测intelligent tester 智能测试仪、诊断仪Recharge 充值CAN communication CAN通信symptom 症状Evaporator 蒸发器ambient temperature 环境温度DTC 故障码Key terms:Step 1 A maintenance case is provided;Ste
34、p 2 Learn the process of air conditioning system service via a maintenance manual;Step 3 Require students to grasp the key terms in this task;Step 4 Try to describe the process of air conditioning system service;Step 5 Students read relative material;Step 6 AssessmentPlan and Implement ()1.After the
35、 vehicle is brought to workshop,the first thing to do is inspecting battery voltage.()2.Replace the battery if the voltage is below 11V.()3.If CAN DTC is output,maybe the CAN Communication System is in trouble.()4.It is enough to check for DTC only once.()5.All of the customers requirements should b
36、e customized.Assessment and Feedback True or False()6.When troubleshooting a function,dont consider where the function is set.()7.When you check for DTC,you should start the engine and warm it up.()8.DTC is usually obtained by the aid of an intelligent tester.()9.If the DTC 00 is displayed,that mean
37、s the sensor should be replaced.()10.Push the“OFF”switch to enter the actuator check mode.8.2.1 How to Repair Air Conditioning in a Car An auto air conditioner is essentially a big refrigerator in which many things can go wrong.There are five main elements of the auto air conditioner that can malfun
38、ction:thecompressor,condenser,receiver-dryer,expansion valve and evaporator.By familiarizing yourself with these five parts,you can have an easy time diagnosing anything that goes wrong.Instructions 1.Be familiar with all the major components of your air conditioning system.This includes the compres
39、sor,the refrigerant,the condenser,the expansion valve,the evaporatorand the receiver-dryer.2.Check to see if any of your refrigerant is leaking out.While leaks are easy to find,they can be difficult to repair.To check for leaks,simply purchase a fluorescent dye from anauto-supply store and add it to
40、 the system following the instructions on the can.3.Check to see if the compressor is turning.Look under the hood while the car is running.The compressor will be the large pump like objects that has rubber and steel hoses attached to it.Make sure the compressors clutch is working when you turn on th
41、e air conditioning.4.Check for anything that needs to be replaced.This can include bad switches,bad fuses,broken wires,a broken fan belt or seal failure in the compressor.5.Remove as much contaminated compressor oil as you can.To do this,you will have to flush the air conditioning system to get rid
42、of the old oil.Then place new compressor oil and restart the car to see if the air conditioning starts to work.6.Use approved flushing agents to clear out the condenser sincethese will evaporate quickly and wont leave a residue inside the system.Depending on the extent of the damage you may also nee
43、d to replace the entire condenser.7.Whenever you are cleaning or replacing the compressor it is also a good idea to replace the accumulators or receiver driers.You should consider the accumulator or receiver dryer to be about the same as an oil filter.These can build up with debris that canaffect th
44、e performance of your air-conditioning system.8.The expansion valve should be replaced regularly,since even small amounts of debris can affect the natural flow of the refrigerant.There is no repair for restricted expansion valves.However,you can try and test them with a replacement compressor before
45、 replacing them to ensure this is the problem.Practice Maintenance Manual Reading How to Proceed with TroubleshootingHINT:Use the following procedures to troubleshoot the air conditioning system.*:Use the intelligent tester.HINT：Refer to the DTC CHECK/CLEAR.(b)Delete the DTCS(c)Recheck for DTCs.Base
46、d on the DTCs output above,try to force output of the A/C system DTC by simulating the operation indicated by the DTC.Practice Maintenance Manual Reading Customize ParametersHINT:The following items can be customized.NOTICE:When the customer requests a change in a function,first make sure that the f
47、unctioncan be customized.Be sure to make a note of the current settings before customizing.When troubleshooting a function,first make sure that the function is set to the default setting.Practice Maintenance Manual Reading Practice Maintenance Manual Reading DTC Check/ClearHINT*:For AUTO A/C1.DTC CH
48、ECK(SENSOR CHECK)*(a)Start the engine and warm it up.(b)Perform the indicator check.HINT:After the indicator check is completed,the system enters the DTC check modeautomatically.(c)Read the code displayed on the panel.(Trouble codes are output on the temperature display.)Practice Maintenance Manual
49、Reading NOTICE:In the sensor check mode,which is automatically transferred from the indicator check mode,troubleshooting may be partially performed.Be sure to perform the actuator check,and then the sensor check again.IF the check is performed in a dark place,DTC 21 or 24 may be displayed even thoug
50、h the system is normal.HINT:Refer to the DTC chart(Diagnostic Trouble Code chart)for details of the codes.When there are no problems,DTC 00 is output.As an example,the illustration shows that display code 21 is output.(d)If the steps are difficult to read because they change automatically,push the“M
