Residual engine heat utilization function

N83.40-2053-02

Shown with code (HZ7) Regulated air conditioning (Tempmatic) in passenger compartment

98/4 Temperature display

98/6 Air distribution duct indicator

98/9 Display of residual engine heat utilization system (REST)

98/15 Display

S98 Air conditioning operating module

S98s8 Air distribution switch

S98s10 Temperature control button

S98s11 Blower control button

S98s12 EC/residual heat system and rear air conditioning button

Function requirements:

 Circuit 15 OFF

 No battery voltage

The residual engine heat utilization makes it possible to heat the vehicle for a period of 30 min. The residual engine heat utilization system (REST) uses the residual heat of the engine for this purpose.

Activation

The REST is activated by pushing the EC or residual heat system and rear air conditioning button (S98s12) in the upper subfield. The activation of the REST is shown via the residual engine heat utilization system display (REST) (98/9) on the display (98/15) of the air conditioning operating module (S98). After being activated, the air conditioning operating module (S98) regulates the coolant circulation pump (M13/5), the water valve (Y19/2), the blending air flap actuator motor (M16/8), and the blower motor (M2) depending on the specified temperature set using the temperature control button (S98s10).

-----------------------------------------------------------------------------------------

The coolant circulation pump (M13/5) ensures that the coolant is circulated. The water valve (Y19/2) determines the flow rate of the coolant through the front heat exchanger. The blending air flap actuator motor (M16/8) adjusts the blending air and shutoff valve thus regulating the air flow which blows by the front heat exchanger. The blower motor (M2) delivers the heated air from the A/C housing, dependent upon the position of the air distribution switch (S98s8) integrated in the air conditioning operating module (S98), via the air outlets to the vehicle interior. The current position of the air distribution flap is shown via the air distribution indicator (98/6) on the display (98/15) of the air conditioning operating module (S98).

 The blower motor (M2) is actuated using the blower regulator (M2n1) with a power output of 39 %, in other words the blower motor (M2) is always operated with
stage 2, even when another blower motor stage (M2) was set using the blower control button (S98s11) integrated in the air conditioning operating module (S98).

-----------------------------------------------------------------------------------------

 When the specified temperature in the air conditioning operating module (S98) is set to 16 °C (maximum cooling) using the temperature control button (S98s10), the temperature is controlled to approx. 18 °C. The set specified temperature is shown via the temperature indicator (98/4) on the display (98/15) of the air conditioning operating module (S98).

Deactivation

The REST is deactivated if of one of the following states applies:

 The EC or residual heat system and rear air conditioning button (S98s12) in the upper subfield is activated again.

 The status "circuit 15 ON" (ignition on) is activated.

 After expiration of an operating time of 30 min

 The battery voltage drops below 11.5 V.