Und auch die Erklärung gefunden wieviele Sensoren den den Lüfter steuern :
" IAT1 is the temperature at the Mass Air Flow sensor (MAF) that is just after the air filter. IAT2 is the inlet air temperature in the intake manifold (after the turbo compression, after the Charge Air Cooler, and after the EGR flow mixes with the air).
The strategy that the PCM uses is complicated:
Engine temperature is not the only parameter that the PCM monitors to determine cooling fan operation. This is the reason that you will see some variation in engine temperature as it correlates to fan operation. The operation/description of the FSS (Fan Speed Sensor) from the PC/ED manual has a fairly good explanation as to how the system "thinks". This is not your traditional engine hits temp X and the fan clutch locks up. The fan speed sensor is a Hall-Effect sensor integral to the vistronic drive fan (VDF). The powertrain control module (PCM) will monitor sensor inputs and control the VDF speed based upon engine coolant temperature (ECT), engine oil temperature (EOT),transmission fluid temperature (TFT) and intake air temperature (IAT) requirements. Also, the air conditioner high side pressure switch will cause the fan high speed to activate (ACP V). When an increase in fan speed for vehicle cooling is requested, the PCM will monitor the FSS signal and output the required pulse width modulated (PWM) signal to a fluid port valve within the VDF. At least one person has seen the factory gauge go from normal to the "red" quickly. It happened around 240 degrees F.
Dual Function Pressure Switch — 6.0L Diesel: The dual function pressure switch (DFPS) is used to interrupt A/C compressor operation in the event of high system discharge pressures. The dual function pressure switch is mounted on a Schrader valve-type fitting on the high pressure side of the compressor manifold and tube assembly. A valve depressor, located inside the threaded end of the DFPS, presses on the Schrader valve stem. This allows the DFPS to monitor the compressor discharge pressure. The DFPS has two sets of electrical contacts. One set of contacts is normally closed and is used for A/C high pressure cutoff. When the A/C compressor discharge pressure rises, the switch contacts open, disengaging the A/C compressor. When the compressor discharge pressure drops, the switch contacts return to the closed position, and A/C compressor operation resumes. For specifications regarding operating pressures, refer to Section 412-00. The second set of electrical contacts in the DFPS is used for engine cooling fan control. It is not necessary to recover the refrigerant to remove the DFPS.
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Filmchen von heute, ich bin auf der richtigen Fährte
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