GF88.79-P-2000QA Heat Left/Right Outside Rearview Mirrors Function

GF88.79-P-2000QA Heat Left/right Outside Rearview Mirrors Function
- as of 1.6.04

Component Identification:

Function requirements
^ Circuit 61 ON (engine running)
^ Voltage not to high or too low
^ Power window not operated

Function
The mirror heater (M21/1r1) in the left electrically adjustable and heated outside mirror (M21/1) and the mirror heater (M21/2r1) in the right electrically adjustable and heated outside mirror (M21/2) each consist of one heating resistor located on a foil on the rear of the mirror lens.
The AAC control and operating unit (N22) or the comfort AAC control and operating unit (N22/7) calculates the dew point from the outside temperature and the air humidity.
The mirror heater (M21/1r1, M21/2r1) is switched on and off depending on the dew point and outside temperature:
^ Outside temperature ≤ 6 °C + dew point, the mirror heater (M21/1r1, M21/2r1) is switched on.
^ Outside temperature ≥ 11 °C + dew point, the mirror heater (M21/1r1, M21/2r1) is switched off.

If no dew point is available, a substitute value of 13 °C is assumed. If the outdoor temperature value received is not plausible, the mirror heater (M21/1r1 and M21/2r1) is switched on.
The request signal is relayed by the AAC control and operating unit (N22) or the comfort AAC control and operating unit (N22/7) to left door control unit (N69/1) and right door control unit (N69/2) via CAN-B (CAN-B). They supply voltage for the corresponding mirror heater (M21/1r1, M21/2r1).

On vehicles as of 1.6.04 it is no longer possible to manually switch on the mirror heater (M21/1r1, M21/2r1) in combination with the rear window heater.