全自動(dòng)空調(diào)系統(tǒng)培訓(xùn)課件分解

1、FULL AUTOMATICAIR CONDITIONINGSYSTEM（FATC）FULL AUTOMATICSYSTEM SPECIFICATION類(lèi)型潤(rùn)滑油 (FD46XG)排量熱保險(xiǎn)絲H/P (off)H/P (on)M/P (off)M/P (on)L/P (off)L/P (on) H/P: 高壓, M/P: 中壓 L/P: 低壓三元壓力開(kāi)關(guān)32.0 2.011.5 1.22.3 0.252.0 0.226.0 2.015.5 0.8說(shuō)明組成HS-18 (SWASH TYPE)184 OFF壓縮機(jī)制冷劑與添加量180cc/revR134a, 68025g150 10cc kg/GS

2、YSTEM SPECIFICATION類(lèi)型潤(rùn)滑油 (FD4SYSTEM LOCATIONA/C 繼電器鼓風(fēng)機(jī)繼電器高速繼電器壓縮機(jī)儲(chǔ)液干燥罐AQS加熱/蒸發(fā)器濕度傳感器FATC模塊室內(nèi)溫度傳感器Amb傳感器光照傳感器功率三極管CONDENSERSYSTEM LOCATIONA/C 繼電器鼓風(fēng)機(jī)繼電器高速部件位置索引 制冷管路更換：HA-31膨脹閥壓縮機(jī)更換：HA-36檢查：HA-37分解：HA-39三元壓力開(kāi)關(guān)電路圖：HA-45冷凝器更換：HA-43冷凝器風(fēng)扇部件：HA-41室外溫度傳感器檢查：HA-53A.Q.S(空氣質(zhì)量傳感器)檢查：HA-51部件位置索引 制冷管路膨脹閥壓縮機(jī)三元壓力開(kāi)關(guān)

3、冷凝器室外溫度REFRIGERANT CIRCUITREFRIGERANT CIRCUITCONDENSERR-134A, PARALLEL FLOW TYPE 蛇 行 式 平 行 式 CONDENSERR-134A, PARALLEL FLOWRelease the high pressurized refrigerant and oil - Operating pressure: 35.342.2kg/COMPRESSOR (SWASH PLATE TYPE)安全閥 (Pressure Relief Valve)Release the high pressurized rTHERMAL F

4、USE皮帶保護(hù) (184 OFF)THERMAL FUSE皮帶保護(hù) (184 OFF)3) 蒸汽泡的分離2) 制冷劑存儲(chǔ)VaporLiquidDESICCANT FILTER PAD FILTER PADFUNCTION1) 制冷劑凈化RECEIVER/DRIVER3) 蒸汽泡的分離2) 制冷劑存儲(chǔ)VaporLiquidDETRIPLE SWITCHMEDIUM (3)MEDIUM (4)LOW & HIGH (1)LOW & HIGH (2)LOWHIGHMEDIUM(1) (3) (4) (2)ELECTRIC DIAGRAM高壓&低壓: 壓縮機(jī)控制中壓 : 冷凝器風(fēng)扇控制高壓中壓低壓EC

5、MTRIPLE SWITCHMEDIUM (3)MEDIUM TRIPLE SWITCH壓力 (Kg/cm2)壓縮機(jī)冷凝器風(fēng)扇備注ONONONONONONONOFFOFFOFF2.3 15.515.5 32.032.0 26.0 11.511.5 2.0壓力升高壓力升高壓力降低壓力降低壓力過(guò)高1. 壓縮機(jī) & 冷凝器風(fēng)扇控制表TRIPLE SWITCH壓力 (Kg/cm2)壓縮機(jī)冷凝器TRIPLE SWITCH 低壓 & 高壓開(kāi)關(guān) (kg/cm2) 中壓開(kāi)關(guān) (kg/cm2)ONOFF11.51.215.50.8ONOFF2.00.22.30.25262.0322.02. SWITCH ON

6、& OFF RANGE(高壓)(低壓)(中壓)TRIPLE SWITCH 低壓 & 高壓開(kāi)關(guān) (kg/cm電路示意圖MMA/CCOMP.MIDHIGH/LOWA/C outputB+B+A/C “ON” inputA/C pressure switch inputFIN SENSORA/C RELAYCON.FANRAD.FANA/C relay controlECMFATC CONTROL MODULE電路示意圖MMA/CCOMP.MIDHIGH/A/C outFATC INPUT & OUTPUTCONTROLMODULEAMB傳感器FIN傳感器室內(nèi)溫度傳感器光照傳感器濕度傳感器AQS傳感

7、器AUTO 開(kāi)關(guān)OFF 開(kāi)關(guān)A/C開(kāi)關(guān)AQS開(kāi)關(guān)AMB開(kāi)關(guān)TEMP開(kāi)關(guān)DEF開(kāi)關(guān)BLOWER開(kāi)關(guān)MODE開(kāi)關(guān)INTAKE開(kāi)關(guān)顯示鼓風(fēng)機(jī)高速繼電器功率三極管溫度門(mén)執(zhí)行器模式執(zhí)行器ECM溫度門(mén)模式門(mén)壓縮機(jī)INPUTOUTPUT功率三極管內(nèi)外循環(huán)執(zhí)行器AQS 控制進(jìn)氣門(mén)FATC INPUT & OUTPUTCONTROLAMB傳HEATER UNITHEATER UNITHEATER UNITFRERECBLOWER MOTOREVAPORATORHEATER COREFLOORMODEDOORVENTMIXDEFINTAKEDOORTEMP. DOOR (MAX HOT)HEATER UNITFR

8、ERECBLOWER MOTOREHEATER UNITFRE外REC內(nèi)BLOWER MOTOREVAPORATORHEATER COREFLOORMODEDOORVENTMIXDEFINTAKEDOORTEMP. DOOR(MAX COOL)HEATER UNITFRERECBLOWER MOTORE部件示意圖 編號(hào)名稱(chēng)編號(hào)名稱(chēng)1室內(nèi)空氣循環(huán)進(jìn)氣孔8除霜通風(fēng)門(mén)（上風(fēng)門(mén)）2室外空氣進(jìn)氣孔9儀表盤(pán)罩通風(fēng)門(mén)（中風(fēng)門(mén)）3除霜通氣孔（上風(fēng)口）10底板通風(fēng)門(mén)（下風(fēng)門(mén)）4儀表盤(pán)罩通風(fēng)孔（中風(fēng)口）11空氣濾清器5底板通風(fēng)孔（下風(fēng)口）12鼓風(fēng)機(jī)總成6內(nèi)外氣選擇風(fēng)門(mén)13蒸發(fā)器芯7溫度控制風(fēng)門(mén)14加熱器芯部件示意

9、圖 編號(hào)名稱(chēng)編號(hào)名稱(chēng)1室內(nèi)空氣循環(huán)進(jìn)氣孔8除MAX A/C模式 當(dāng)選擇MAX A/C時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室內(nèi)空氣循環(huán)- 溫度控制風(fēng)門(mén)：最冷- 除霜通風(fēng)門(mén)：關(guān)閉- 儀表盤(pán)罩通風(fēng)門(mén)：打開(kāi)- 底板通風(fēng)門(mén)：關(guān)閉- 空調(diào)壓縮機(jī)：ON- 鼓風(fēng)機(jī)電機(jī)：ONMAX A/C模式 當(dāng)選擇MAX A/C時(shí)：A/C模式 當(dāng)選擇A/C時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室外空氣進(jìn)入- 溫度控制風(fēng)門(mén)：可以選擇- 除霜通風(fēng)門(mén)：可以選擇- 儀表盤(pán)罩通風(fēng)門(mén)：可以選擇- 底板通風(fēng)門(mén)：可以選擇- 空調(diào)壓縮機(jī)：ON- 鼓風(fēng)機(jī)電機(jī)：ONA/C模式 當(dāng)選擇A/C時(shí)：儀表盤(pán)罩（中風(fēng)口）模式 當(dāng)當(dāng)選擇儀表盤(pán)罩時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室外空氣進(jìn)入-

10、溫度控制風(fēng)門(mén)：可以選擇- 除霜通風(fēng)門(mén)：關(guān)閉- 儀表盤(pán)罩通風(fēng)門(mén)：打開(kāi)- 底板通風(fēng)門(mén)：關(guān)閉- 空調(diào)壓縮機(jī)：可以選擇- 鼓風(fēng)機(jī)電機(jī)：ON儀表盤(pán)罩（中風(fēng)口）模式 當(dāng)當(dāng)選擇儀表盤(pán)罩時(shí)：OFF 當(dāng)選擇OFF時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室內(nèi)空氣循環(huán)- 溫度控制風(fēng)門(mén)：可以選擇- 除霜通風(fēng)門(mén)：打開(kāi)- 儀表盤(pán)罩通風(fēng)門(mén)：關(guān)閉- 底板通風(fēng)門(mén)：關(guān)閉- 空調(diào)壓縮機(jī)：OFF- 鼓風(fēng)機(jī)電機(jī)：OFFOFF 當(dāng)選擇OFF時(shí)：儀表盤(pán)罩/底板（中風(fēng)口/下風(fēng)口）模式 當(dāng)選擇儀表盤(pán)罩/底板時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室外空氣進(jìn)入- 溫度控制風(fēng)門(mén)：可以選擇- 除霜通風(fēng)門(mén)：關(guān)閉- 儀表盤(pán)罩通風(fēng)門(mén)：打開(kāi)- 底板通風(fēng)門(mén)：打開(kāi)- 空調(diào)壓縮機(jī)：可以選擇-

11、鼓風(fēng)機(jī)電機(jī)：ON儀表盤(pán)罩/底板（中風(fēng)口/下風(fēng)口）模式 當(dāng)選擇儀表盤(pán)罩/底板底板（下風(fēng)口）模式 當(dāng)選擇底板時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室外空氣進(jìn)入- 溫度控制風(fēng)門(mén)：可以選擇- 除霜通風(fēng)門(mén)：關(guān)閉- 儀表盤(pán)罩通風(fēng)門(mén)：關(guān)閉- 底板通風(fēng)門(mén)：打開(kāi)- 空調(diào)壓縮機(jī)：可以選擇- 鼓風(fēng)機(jī)電機(jī)：ON底板（下風(fēng)口）模式 當(dāng)選擇底板時(shí)：底板/除霜（下風(fēng)口/上風(fēng)口）模式 當(dāng)選擇底板/除霜模式時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室外空氣進(jìn)入- 溫度控制風(fēng)門(mén)：可以選擇- 除霜通風(fēng)門(mén)：打開(kāi)- 儀表盤(pán)罩通風(fēng)門(mén)：關(guān)閉- 底板通風(fēng)門(mén)：打開(kāi)- 空調(diào)壓縮機(jī)：可以選擇- 鼓風(fēng)機(jī)電機(jī)：ON底板/除霜（下風(fēng)口/上風(fēng)口）模式 當(dāng)選擇底板/除霜模式時(shí)：除霜（上風(fēng)

12、口）模式當(dāng)選擇除霜模式時(shí)：- 內(nèi)外氣選擇風(fēng)門(mén)：室外空氣進(jìn)入- 溫度控制風(fēng)門(mén)：可以選擇- 除霜通風(fēng)門(mén)：打開(kāi)- 儀表盤(pán)罩通風(fēng)門(mén)：關(guān)閉- 底板通風(fēng)門(mén)：關(guān)閉- 空調(diào)壓縮機(jī)：ON- 鼓風(fēng)機(jī)電機(jī)：ON除霜（上風(fēng)口）模式當(dāng)選擇除霜模式時(shí)：EVAPORATOR UNITEVAPORATOR UNITEVAPORATOR AND BLOWER UNIT1. 前視圖FIN 傳感器濾清器大功率三極管進(jìn)氣門(mén)執(zhí)行器鼓風(fēng)機(jī)馬達(dá)風(fēng)機(jī)繼電器高速繼電器EVAPORATOR AND BLOWER UNIT1. 前EVAPORATOR AND BLOWER UNIT2. 后視圖 冷凝劑出口冷凝劑入口 鼓風(fēng)機(jī)馬達(dá)排放管進(jìn)氣門(mén)執(zhí)行器進(jìn)

13、氣門(mén)EVAPORATOR AND BLOWER UNIT2. 后EVAPORATOR AIR FILTER1. DESCRIPTIONEmploying combination filter, dust and odor in the air is effectively removed.2. LIFE TIMEFilter replacement period is 5,000 12,000km. But this can be shorten if the road condition is bad causing more dust and black smoke in the air.

14、3. HOW TO REPLACE Remove the glove box. Pull the locking part of the air filter coverAir filter coverEVAPORATOR AIR FILTER1. DESCRIEVAPORATOR AIR FILTERCAUTION!Make sure that arrow mark on the filter is pointing the evaporator core side.EVAPORATOR AIR FILTERCAUTION!BLOWER MOTOR ASSEMBLY+ PIN- PINMot

15、or : magnet motor(70) 額定電壓 : 12V 無(wú)負(fù)載 - speed : 3300 rpm (min) - current : 3.0A (max) 有負(fù)載 - rated load : 4.4 kgf-cm - speed : 2900 300 rpm - current : 18.3 1.3A (max) 工作溫度 -30 80 BLOWER MOTOR ASSEMBLY+ PIN- PIBLOWER SPEED CONTROL DEVICE1. 功率三極管 安裝位置POWER TRBLOWER SPEED CONTROL DEVICE1. BLOWER SPEED C

16、ONTROL DEVICE POWER TR AND PIN ASSIGNMENT COLLECTORBASEEMITTERBLOWER SPEED CONTROL DEVICE PMBATTERYIG2BLOWERMOTORMeasure voltagevCONTROLLER(B+ : 12V)POWER TRHIGH SPEED BLOWER RELAYBLOWER RELAYBCE* CONDITION: IG ON, FATC ON POWER TR INSPECTION METHOD 1BLOWER SPEED CONTROL DEVICEMBATTERYIG2BLOWERMeasu

17、re voltaMBATTERYIG2BLOWERMOTORMeasure voltage: B+vCONTROLLERPOWER TRHIGH SPEED BLOWER RELAYBLOWER RELAYBCEv POWER TR INSPECTION METHOD 2* CONDITION: IG ON, FATC OFFMeasure voltage:Variable (up/down blower speed switch) * CAUTION: Do not pull off the TR during blower operation.BLOWER SPEED CONTROL DE

18、VICEMBATTERYIG2BLOWERMeasure voltaHIGH SPEED BLOWR RELAYBLOWER SPEED CONTROL DEVICE2. 鼓風(fēng)機(jī)高速繼電器 安裝位置HIGH SPEED BLOWR RELAYBLOWER SINTAKE ACTUATORFATCMCCWCWRECFRERECFRE - +-+端子編號(hào)NO. 1NO. 2模式V* 電壓檢測(cè)時(shí)按下此開(kāi)關(guān)12+-+-INTAKE ACTUATORFATCMCCWCWRECFRTEMP DOOR ACTUATOR TEMP DOOR ACTUATOR is located in the bottom

19、of the heater unit. The actuator controls the position of the temperature blend door based on the voltage signal from the FATC module. Potentiometer inside actuator sends a feedback signal to the controller and controller cuts off the the voltage signal coming from the controller when the required d

20、oor position is achieved.Temp door actuator23451connectorPOTENTIOMETER CHARACTERISTICSWhen 5V between pin 3-5, above voltage is obtained between pin 4-5.22COOLHOT4.7V0.3VTEMP DOOR ACTUATOR TEMP DOOR AMODE ACTUATORMMICOMMODEMODE S/WDRIVEICMODEVENTBi-LEVFLOORM I XDEF VENT BI-LEVEL FLOOR MIX DEF* G: Gr

21、oundIG2(+)GROUNDIC G + + + + + G + + + + + G + + + + + G + + + + + G MODE ACTUATORMMMODEMODE S/WDMOTEMP DOOR ACTUATORFATCM+-MICOMVcc(+)5VActuatorCOOLWARM4.7V0.3VTEMP S/W2.5V* Feedback line open or short: 選擇1724.5 : MAX COOL位置 選擇 2532 : MAX HOT位置TEMP DOOR ACTUATORFATCM+-MICCONNECTORFIN SENSOR1. DESCR

22、IPTIONFin sensor are installed in the evaporator in order to detect the temperatureof evaporator. It prevent evaporator from freezing. 2. FIN SENSOR LOCATION : inserted into the evaporator pin2 1CONNECTORFIN SENSOR1. DESCRIPTFIN SENSOR CHARACTERISTICS OF FIN SENSOR ON/OFF TEMPERATURE: 0 0.5 OFF 3.5

23、4 ON FIN SENSOR CHARACTERISTICS OFINCAR SENSORThe in-car sensor is located in the FATC control pannel. it contains a thermistor, which measures the temperature of the air inside the passenger compartment. It senses the passenger compartment temperature, changes the resistance value, and enters the c

24、orresponding voltage into the automatic temperature control module (FATC).INCAR SENSORThe in-car sensor INCAR SENSORThe in-car sensor is located inside FATC controller. Type : Aspirator hoseINSTALL LOCATIONIn-car sensor with aspirator hoseINCAR SENSORThe in-car sensor INSPECTION Resistance character

25、istic (NTC: negative thermal coefficient)* MEASUREMENTINSPECTION Resistance charactPHOTO SENSORThe photo sensor is located on the center of crash pad assembly. It contains a photovoltaic (sensitive to sunlight) diode. Characteristics of photo sensorPHOTO SENSORThe photo sensor iPHOTO SENSOR (FATC)IN

26、SPECTION60w(Over 0.45V )10 15cm+-PHOTO SENSOR (FATC)INSPECTION6AMBIENT SENSORThe ambient temperature sensor is located in front of the condenser fan shroud. This sensor detects the temperature of outside air and sends voltage signals to the controller.TemperatureResistanceVoltage(V)TemperatureResist

27、anceVoltage(V)-10157.8 4.201058.8 3.31-5122.0 4.012037.3 2.77095.0 3.803024.3 2.24574.5 3.564016.1 1.75AMBIENT SENSORThe ambient tempAMBIENT SENSOR (FATC) FATCMICOM5VSENSORGROUNDVOLTAGEDETECTION (B3) (B16)INSPECTIONREFERERANCEVOLTAGE* Resistance between & Resistance characteristic:(NTC: negative the

28、rmal coefficient)Resistance()Temperature()AMBIENT SENSOR (FATC) FATCM5VSAQS (FATC OPTION)The Air Quality System detects exhaust gas of neighboring vehicles and intercepts automatically. AQS controls the inlet of car automatically and can be easily installed to the existing vehicle. Manual operation

29、is also available.SPECIFICATIONOperating voltage9 16V DCRated voltage12V DCOperating temperature-30 105 Detectable gasGasoline engine gasCXHY, CODiesel engine gasNOX, SO2Reaction timeless 1 secAQS (FATC OPTION)The Air QualiAQS (FATC OPTION)* LOCATION: In front of condenser* AQS SWITCHAQS (FATC OPTIO

30、N)* LOCATION: IAQS (FATC OPTION)IG 12VOUTPUTGASdetected(REC)Normal(FRE)MccwcwINTAKEACTUATORFATCCONTROLMODULE- Normal 5V - Gas detected 0V AQSAQS (FATC OPTION)IG 12VOUTPUTGHUMIDITY SENSOR (OPTION WITH AQS)Humidity sensor detects the relative humidity of the cars cabin. This sensor converts it into th

31、e voltage signal and sends the signal to the FATC controller. 1. SENSOR CHARACTERISTICSHUMIDITY SENSOR (OPTION WITH AHUMIDITY SENSOR (OPTION WITH AQS)-25-20-1510-5051015202530354045502030405060708090100 CABIN RELATIVE HUMIDITY (%)AMBIENT TEMPERATURE ()(-20,90)(5,90)(25,30)(45,30)A/C ONA/C OFFHYSTERE

32、SIS RANGEHUMIDITY SENSOR (OPTION WITH A 2. SPECIFICATIONS 1). Sensor type: High polymer impedance variation sensor 2). Rated voltage: DC 5V. 3). Current consumption: below 10 mA 4). Temperature range: 0 - 60 5). Humidity range: below 99% RH(Relative Humidity) 6). Terminals: 3 terminals ( DC 5V, Grou

33、nd, Sensor output) 3. Block DiagramHUMIDITY SENSOR (OPTION WITH AQS) 2. SPECIFICATIONSHUMIDITY SEHUMIDITY SENSOR (OPTION WITH AQS)LOCATION: on the center of rear seat trimHUMIDITY SENSOR (OPTION WITH A控制面板 (FATC, AQS)AQSswitchFre/RecswitchAmbient temperaturecheck switchA/C ON/OFFswitchRear defogswit

34、chDefrostswitchBlower speedup/down switchA/C AUTOswitchSystem OFFswitchModeswitchTemperatureup/down switch1. FATC WITH AQS控制面板 (FATC, AQS)AQSswitchFre/控制面板風(fēng)速選擇共 7擋狀態(tài)顯示畫(huà)面溫度選擇按鈕17 32自動(dòng)室內(nèi)溫度傳感器選擇AQS功能選擇空調(diào)選擇風(fēng)向除霜(后窗及倒車(chē)鏡)除霧確認(rèn)外界溫度控制面板風(fēng)速選擇狀態(tài)顯示畫(huà)面溫度選擇按鈕自動(dòng)室內(nèi)溫度傳感器選TEMPERATURE UNIT CHANGE* Setting unit: (Battery

35、disconnection)Temp unit change: Keep pressingPress for 3 seconds or more*How to operateTEMPERATURE UNIT CHANGE* SettiCONTROL PANNEL SWITCH FUNCTIONCONTROL PANNEL SWITCH FUNCTIONCONTROL PANNEL SWITCH FUNCTION* VENT B/L FLOOR MIX VENTCONTROL PANNEL SWITCH FUNCTIONCONTROL PANNEL SWITCH FUNCTIONCONTROL

36、PANNEL SWITCH FUNCTION1. 室內(nèi)溫度傳感器修正 When the in-car sensor detects a sudden steep temperature change, controller corrects the temperature differences slowly.- 1 up / 4sec delay- 1 down / 4sec delay2. 室外溫度傳感器修正 When the ambient sensor detects a sudden steep temperature change, controller corrects the

37、temperature differences slowly.- 1 up / 3 min delay (ex. Underground, tunnel)- 1 down / 4sec delayCONTROL LOGIC1. 室內(nèi)溫度傳感器修正CONTROL LOGIC3. 熱輻射修正 When the photo sensor detects a sudden steep solar radiation change, controller compensates it slowly.- 350 1000 (W/m2) / 1 min delay- 350 1000 (W/m2) / 5

38、min delay4. 溫度門(mén)控制 Temp. door angle (0% 100%) is automatically controlled according to the selected temperature and other sensor signals. Available selected temperature range - MAX COOL: 17 - MAX HOT: 32 - 17 32, 0.5 step (62 90, 1 step)CONTROL LOGIC3. 熱輻射修正CONTROL LOGIC5. 鼓風(fēng)機(jī)轉(zhuǎn)速控制 - 自動(dòng)模式: 線(xiàn)性控制 - 手動(dòng)模式

39、: 7 檔6. 模式控制 - 自動(dòng)模式: 根據(jù)選擇的溫度和其它的傳感器信號(hào)，自動(dòng)控制模式的變化. - 手動(dòng)模式: 根據(jù)手動(dòng)選擇改變模式.VENT B/L FLOOR MIX VENT如果選擇此模式空調(diào)壓縮機(jī)工作CONTROL LOGIC5. 鼓風(fēng)機(jī)轉(zhuǎn)速控制VENT B/L FLOOR 7. 內(nèi)外循環(huán)控制模式 - The FRE/REC door state can be changed at AUTO mode according to the input data combination.8. 壓縮機(jī)控制 (AUTO mode) - Fin sensor: under 0.5 Compressor OFF over 3 Compressor ON9. MAX HOT功能(When 32 is selected at AUTO mode) 溫控門(mén): MAX HOT side 模式門(mén): Floor mode 進(jìn)氣門(mén): FRE mod 壓縮機(jī): OFF 鼓風(fēng)機(jī)轉(zhuǎn)速: MAX highCONTROL LOGIC7. 內(nèi)外循環(huán)控制模式CONTROL LOGIC10. MAX COOL 功能 (When 17is selected at AUTO mode) 溫控門(mén): MAX COOL side 模式門(mén): VENT mode 進(jìn)氣門(mén): REC mod