560SL (107.048) V8-5.6L (117.967) (1989)
Coolant Temperature Sensor / Switch HVAC: Description and Operation
Cold Engine Lock-out Switch (S71)
The temperature switch (2) (cold engine lock) prevents the heating system from starting at a coolant temperature below 33°C in function "c" and "d" and
thereby prevents that undesired cold air blowing against passengers.