GF83.75-D-2000H Residual Engine Heat Utilization Function

GF83.75-D-2000H Residual Engine Heat Utilization Function

- with CODE (HH9) "Tempmatic" regulated air conditioning

On vehicles with code (HH9) Regulated air conditioning (Tempmatic), the engine residual heat utilization function can be used via the circulation pump (M13/4) up to August 31, 2008.
As of September 1, 2008, this is only possible if one of the following special equipment packages is also installed:
- Code (HZ5) 10 kW auxiliary water heater with timer
- Code (HZ9) Heater booster, diesel
- Code (H12) Auxiliary heater (warm water)
- Code (H13) Additional heat exchanger in cargo area







Shown with code (H13) Additional heat exchanger in load compartment, with code (HH7) Additional air conditioning in rear or with code (H08) High-performance air conditioning
S98 AAC [KLA] control and operating unit
S98s4 AC OFF and residual heat system button
S98s8 Air distribution switch
S98s10 Blower control button (+)
S98s11 Blower control button (-)
S98s14 Temperature selection switch

The function requirement is "tml. 15 OFF" (ignition off). 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 MRA is activated using the AC OFF and residual heat system button. Activation of the MRA is indicated by illumination of the red light emitting diode (LED) in the AC OFF and residual heat system button. After activation, the KLA control and operating unit controls the following components as a function of the position of the temperature selection switch integrated into the KLA control and operating unit:
- Circulation pump
- Blend air flap actuator motor (M16/8)
- Blower motor (M2)

The circulation pump ensures circulation in the coolant circuit.
The blend air flap actuator motor adjusts the blend air and shutoff flap, thus regulating the air flowing past the front heater heat exchanger. The blower motor routes the heated air from the front AC housing over the air outlets into the vehicle interior as a function of the position of the air distribution switch integrated into the KLA control and operating unit.

The blower motor is only ever driven in stage 1, even if another setting is made using the blower control button (+) and the blower control button (-) integrated into the KLA control and operating unit.

If the temperature selection switch integrated into the KLA control and operating unit is set to "MAX cooling" (the temperature selection switch is turned all the way to the left in the detent position), the temperature is regulated to approx. 18 °C.

Deactivation
The REST is deactivated if of one of the following states applies:
- The AC OFF and residual heat system button is pressed again.
- The status "terminal 15 ON" (ignition on) is activated.
- The operating time of 30 min has elapsed.
- The battery voltage drops below 11.5 V.