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The BMW Range
5 Series
E39
E39 Aux fan (electric fan)
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<blockquote data-quote="jarance" data-source="post: 556289" data-attributes="member: 21"><p>Yes, the Speed of the Aux fan depend on the coolant temperature and aircon pressure.</p><p></p><p><u>Extract from BMW WDS</u></p><p></p><p><strong><u>Electric Fan</u></strong></p><p>Vehicles with M62TU, S62 and M73 engines feature a clutch fan as well as an electric fan. The electric fan cuts in when the cooling capacity of the clutch fan is no longer sufficient.</p><p></p><p>The electric fan is activated by means of a power output stage directly on the fan motor. The motor control unit activates this power output stage by means of a square-wave signal with duty factors (variable pulse width) between 10 % and 90 % thus controlling the various speeds of the electric fan. Pulse duty factors less than 5 % and greater than 95 % do not trigger activation but rather they are used for fault detection purposes. The power output stage features its own positive and ground supply.</p><p></p><p>The fan speed is influenced by the <strong>coolant temperature at the radiator outlet</strong> and<strong> the pressure in the air conditioning system</strong>. The fan speed is reduced as the vehicle speed increases.</p><p></p><p>If a fault occurs during operation a corresponding fault code will be stored in the fault code memory of the DME control unit.</p><p></p><p>For the purpose of checking operation and troubleshooting, the diagnostic program offers the option of activating the electric fan directly via the DIS tester/MoDiC</p><p></p><p>Specified values, pressure sensor</p><p>Data on working ranges and substitute values.</p><p></p><p>The pressure sensor receives a 5 volt power supply from the control unit for the heating/air-conditioning system. The sensor signal is evaluated with the help of tables and forwarded to the engine electronic via the K bus. In the process, the refrigerant pressure in the air-conditioning circuit is converted to a load torque and the required fan stage.</p><p><u><strong></strong></u></p><p><u><strong>Refrigerant pressure-fan stage conversion table</strong></u></p><p></p><p>Each fan stage that is determined is transmitted via a BUS from the engine electronics. </p><p>Prerequisite is a speed less than 80 km/h.</p><p></p><p>Pressure in bar - Fan stage</p><p>8--------------------0 (Stop)</p><p>10-------------------1 (Slowest Speed)</p><p>14-------------------2</p><p>15-------------------3</p><p>17-------------------4</p><p>18-------------------5</p><p>19-------------------6</p><p>19-------------------7</p><p>20-------------------8</p><p>21-------------------9</p><p>21-------------------10</p><p>22-------------------11</p><p>23-------------------12</p><p>26-------------------13</p><p>29-------------------14</p><p>> 29----------------15 (fastest speed)</p></blockquote><p></p>
[QUOTE="jarance, post: 556289, member: 21"] Yes, the Speed of the Aux fan depend on the coolant temperature and aircon pressure. [U]Extract from BMW WDS[/U] [B][U]Electric Fan[/U][/B] Vehicles with M62TU, S62 and M73 engines feature a clutch fan as well as an electric fan. The electric fan cuts in when the cooling capacity of the clutch fan is no longer sufficient. The electric fan is activated by means of a power output stage directly on the fan motor. The motor control unit activates this power output stage by means of a square-wave signal with duty factors (variable pulse width) between 10 % and 90 % thus controlling the various speeds of the electric fan. Pulse duty factors less than 5 % and greater than 95 % do not trigger activation but rather they are used for fault detection purposes. The power output stage features its own positive and ground supply. The fan speed is influenced by the [B]coolant temperature at the radiator outlet[/B] and[B] the pressure in the air conditioning system[/B]. The fan speed is reduced as the vehicle speed increases. If a fault occurs during operation a corresponding fault code will be stored in the fault code memory of the DME control unit. For the purpose of checking operation and troubleshooting, the diagnostic program offers the option of activating the electric fan directly via the DIS tester/MoDiC Specified values, pressure sensor Data on working ranges and substitute values. The pressure sensor receives a 5 volt power supply from the control unit for the heating/air-conditioning system. The sensor signal is evaluated with the help of tables and forwarded to the engine electronic via the K bus. In the process, the refrigerant pressure in the air-conditioning circuit is converted to a load torque and the required fan stage. [U][B] Refrigerant pressure-fan stage conversion table[/B][/U] Each fan stage that is determined is transmitted via a BUS from the engine electronics. Prerequisite is a speed less than 80 km/h. Pressure in bar - Fan stage 8--------------------0 (Stop) 10-------------------1 (Slowest Speed) 14-------------------2 15-------------------3 17-------------------4 18-------------------5 19-------------------6 19-------------------7 20-------------------8 21-------------------9 21-------------------10 22-------------------11 23-------------------12 26-------------------13 29-------------------14 > 29----------------15 (fastest speed) [/QUOTE]
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E39 Aux fan (electric fan)
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