Date registered: Jun 2012
Vehicle: 1998 E320 base sedan @ 160kmiles
Location: Boca Raton, FL
Mentioned: 79 Post(s)
Quoted: 1189 Post(s)
The illumination for the a/c clima unit is controlled by a command from the instrument cluster through interface K1.
From the sensor display menu on the a/c unit display (Pressing REST for more than 5 seconds with a/c unit in AUTO mode).. Increment to item 23 which shows the percentage battery voltage for the illumination. If zero, it is off, and 99 is the max.
Also check the error codes with the diagnostic menu. The b1422 error code indicates a problem with the K1 interface through the illumination level information is supplied.