SLK 32 AMG (170.466) V6-3.2L SC (112.960) (2003)
Heater Control Valve: Description and Operation
Duo Valve
The duovalve controls the quantity of coolant flowing through the heater core.
At low heater setting the pushbutton control module connects the solenoids in the duovalves (A31y1 and A31y2) to ground, the solenoids pull in and
block the coolant flow through the heater core separately for the left and right sides.
At the maximum temperature setting the pushbutton control module Interrupts the ground connection, current no longer flows through the solenoids and
the coolant flow through the heater core is at its maximum.
In the regulated mode the pushbutton control module switches intermittently to ground.
The closing and opening times for the duovalves (A31y1 and A31y2) depend upon the deviation between the temperature measured by the passenger
compartment sensor and the temperature set on the pushbutton control module.
Residual engine heat utilization
Control of the passenger compartment temperature for residual engine heat utilization is the same as when driving, whereby the coolant circulation pump
(A31m1) circulates the coolant.