For Mercedes-Benz Cars
From approximately 1981-1995 there were two predominant systems for HVAC. One system consisted of three pieces of electronics:
Push Button Unit
Temperature Regulator
Blower Motor Control
This system was in use on:
W126: 1981-1985 (First Generation)
W123: 1981-1985
R107: 1981-1989
Component Locations
In the W126 the components are located on the sides blower motor enclosure. (More pictures coming soon)
Blower Motor Controller Shown Below. Temperature Regulator located opposite, on other end of blower motor enclosure.