ECT sensor, function - GF83.40-P-2125-01A

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

Function

The ECT sensor sends a resistance value corresponding to the coolant temperature via the instrument cluster and the serial interference (K1) to the pushbutton control module. Here the value is processed and the A/C compressor is switched off in two stages as follows:

Stage 1

At a coolant temperature >123 °C the duty factor is reduced by 50 %. In this case the A/C compressor is switched on in cycles, i.e. off approx. 20 sec. and on approx. 20 sec.

If the coolant temperature drops to below 123 °C the A/C compressor is switched on again permanently.

Stage 2

At a coolant temperature >127 °C the A/C compressor is switched off completely.

When the coolant temperature drops to below 127 °C the A/C compressor is switched back on in the cycled mode (stage 1).