01%20Climate%20Control%20Part%201, BMW educational info, Dokumentacja

01%20Climate%20Control%20Part%201

01%20Climate%20Control%20Part%201, BMW educational info, Dokumentacja

[ Pobierz całość w formacie PDF ]
//-->TABLE OF CONTENTSSubjectPage225456910111213222425263133353738394142444647495559606265707273Engine Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Coolant Recovery& Level Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Radiator Cap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Main Cooling Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Engine Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ECM Controlled Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Water Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Heater Core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Heater & Air Conditioning System Comparisons . . . . . . . . . . . . . . . . . . . . .Theory of Heat & Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Air Conditioning (A/C) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Refrigerant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Adding Oil to the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Compressor Clutch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Auxiliary Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .R-12 Receiver/Dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Repair Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Proper Reading of the Sight Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .R-134a Receiver/Dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Expansion Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Evaporator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Blower Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Microfilters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Types of Refrigerants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Refrigerant Handling Certification Requirements . . . . . . . . . . . . . . . . . . . . .Leak Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Temperature Sensing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ambient Temperature/Relative Humidty Chart . . . . . . . . . . . . . . . . . . . . . . .Non-Approved Air Conditioning Refrigerants . . . . . . . . . . . . . . . . . . . . . . . .Verified System Malfunction Follow-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Basic Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ENGINE COOLING/PASSENGER COMPARTMENT HEATING SYSTEMENGINE COOLING SYSTEMAt operating temperature, an automotive engine produces excess heat. Heat is a by-prod-uct of all internal combustion engines. Modern engines operate at higher temperaturesand therefore run more efficiently - less of the energy produced by burning fuel is turnedinto heat, and more of the energy is used to power the vehicle. However, they still produceexcess heat.The engine is equipped with a cooling system designed to remove much of the excessheat. When functioning properly, the cooling system maintains an optimum temperaturefor the engine.RADIATORThe radiator is used to dissipate the excessheat from the hot coolant. At operatingtemperature, some of the engine coolantcirculates through the radiator and gives upits heat to the outside air, as it passesacross the radiator. So the radiator is a“heat exchanger.”2COOLANT RECOVERY TANKThe engine cooling system is equipped with areservoir to maintain a constant supply of coolantin the system. When the coolant is hot, itexpands into the reservoir; when it cools, it con-tracts and flows from the reservoir into the radia-tor. The surge tank is transparent, so that thefluid level can be checked periodically, to ensurethat the coolant level is adequate.The level of coolant in the reservoir should beabove the bottom line (“Kalt”) when the engine iscool and below the top line (“Heisse”) when theengine is at operating temperature.COOLANT LEVEL CHECKTo check coolant level, allow engine tocool down; coolant temperature maynot exceed 30ºC. If ambient tempera-ture is above 30ºC, then allow engine tocool down at least to ambient tempera-ture.Check coolant level, top up coolant ifnecessary until float is in line with topedge of expansion tank.Note:Tank mark indicates the fluid level at approx. 20ºC. Use only recommended coolant, referto BMW Service Operating Fluid in Main Group3RADIATOR CAPThe reservoir has a pressure cap, which isdesigned to maintain pressure in the cooling sys-tem. As the engine warms up, coolant tempera-ture increases and the coolant expands. The pres-sure cap prevents the expanding coolant fromescaping and results in a pressure increase in thesystem. This raises the coolant’s boiling point.This allows the cooling system to maintain the cor-rect engine operating temperature without boilingover.Radiator CapThe radiator cap has both pressure and vacuum valves. At the rated pressure, the pres-sure valve opens, to allow vapor to escape into the atmosphere and coolant to flow intothe reservoir due to expansion. This prevents excess pressure from building up in the sys-tem.When the engine is stopped and allowed to cool off, the pressure in the cooling systemdrops from a pressure that is higher than the atmospheric pressure, to one that is lower.At this point, the vacuum valve opens to allow ambient air to enter the reservoir, and pres-sure in the system equals atmospheric pressure. If the coolant level in the radiator is lowduring this period, coolant will be drawn into the radiator.NOTE: Please refer to repair manual group 17 for complete cooling system infor-mation and testing.4MAIN COOLING FANThe radiator is equipped with a main cooling fan that is either electrically powered orengine driven via a belt, the water pump pulley, and a viscous clutch.The viscous clutch reduces fan speed when cooling requirements are low. The clutch con-tains a small fluid coupling partially filled with a special silicone oil. When engine coolingrequirements are high (during high-temperature operation), more oil is injected into the fluidcoupling. This causes more power to pass through the coupling, so that fan speedincreases. When cooling requirements are low (for example, during cool-weather opera-tion), oil is withdrawn from the fluid coupling. Less power passes through and fan speeddrops off.Even when engine cooling requirements are high, there is still a small amount of slip (Thecoupling does not lock up). This allows the oil to continue to circulate through the fluidreservoir and the coupling.The amount of oil in the fluid coupling, and the resulting fan speed, are controlled by athermostatic strip. The strip bows outward with increasing under-the-hood temperature.This motion allows a control piston to move outward. As the piston moves outward, moreoil is forced into the coupling, causing the fan speed to increase.Viscous Clutch5 [ Pobierz całość w formacie PDF ]

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