GF83.57-D-2000H Temperature Control Function
GF83.57-D-2000H Temperature Control Function
- with CODE (HH9) "Tempmatic" regulated air conditioning
On vehicles with code (HH9) Regulated air conditioning (Tempmatic), the circulation pump (M13/4) for the engine residual heat utilization function is installed up to August 31, 2008. As of September 1, 2008, the circulation pump is only available 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
S98b1 In-car temperature sensor
S98s4 AC OFF and residual heat system button
S98s5 Reheat/defrost mode button
S98s8 Air distribution switch
S98s10 Blower control button (+)
S98s11 Blower control button (-)
S98s14 Temperature selection switch
The Tempmatic (TM) enables a pleasant interior climate for the vehicle passengers in the event of different weather conditions.
The TM controls the temperature by cooling the fresh or recirculated air with the aid of the front evaporator or by heating the fresh or recirculated air with the aid of the front heater heat exchanger.
The temperature selection switch integrated in the AAC [KLA] control and operating unit is used to set the desired temperature in the vehicle interior and control it as a function of the following components:
- Evaporator temperature sensor (B10/6)
- Refrigerant pressure sensor (B12)
- Outside air temperature sensor (B14)
- Interior temperature sensor
When the temperature selection switch is turned all the way to the right into the detent position, the "MAX heating" function is activated.
When the temperature selection switch is turned all the way to the left into the detent position, the "MAX heating" function is activated.
When the "MAX heating" function or the "MAX cooling" function is activated, no temperature control takes place in the vehicle interior.
In order to accelerate the temperature increase or decrease, the output of the blower motor (M2) can be adjusted in 5 stages by means of the blower control button (+) and blower control button (-) integrated in the AAC [KLA] control and operating unit and the air distribution can be set by means of the air distribution switch integrated in the AAC [KLA] control and operating unit.
The temperature control of the TM is divided into the following subfunctions:
- Heating mode
- Cooling mode
- Reheat mode (air dehumidification function)
Heating mode
The outside air temperature sensor records current temperature of the outside air and the interior temperature sensor records the current temperature in the vehicle interior. The AAC [KLA] control and operating unit reads in the two values and actuates the two following components according to the specified temperature set at the temperature selection switch:
- Circulation pump
- Blend air flap actuator motor (M16/8)
In combination with the water pump, the circulation pump ensures circulation of the coolant in the coolant circuit. The blend air flap actuator motor adjusts the blend air and shutoff flap, thus regulating the air flow of the fresh or recirculated air which blows by the front heater heat exchanger. With the "MAX heating" function, the AAC [KLA] control and operating unit actuates the blend air flap actuator motor. At the same time, the blend air and shutoff flap is fully opened so that the maximum air flow of fresh or recirculated air blows by the front heater heat exchanger.
Cooling mode
Cooling mode is activated or deactivated by pressing the AC OFF and residual heat system button. Deactivation (economy mode) is indicated by illumination of the red light emitting diode (LED) in the AC OFF and residual heat system button. When cooling mode is activated, the red LED in the AC OFF and residual heat system button goes out.
The AAC [KLA] control and operating unit reads in the AC OFF and residual heat system button and actuates in the event of activation or deactivation the refrigerant compressor (A9) via the refrigerant compressor control valve (A9y1).
The AAC [KLA] control and operating unit reads in the values of the following components:
- Evaporator temperature sensor, it records the current ambient temperature of the front evaporator.
- Refrigerant pressure sensor, it records the current refrigerant pressure in the air conditioning.
- Outside air temperature sensor, with code (J65) Outside temperature indicator, it records the current temperature of the outside air.
- Interior temperature sensor, it records the current temperature in the vehicle interior.
The AAC [KLA] control and operating unit reads in the 4 values and regulates the refrigerant compressor with the aid of the refrigerant compressor control valve and the blend air flap actuator motor according to the specified temperature set with the aid of the temperature selection switch.
The blend air flap actuator motor adjusts the blend air and shutoff flap, thus regulating the air flow of the fresh or recirculated air which blows by the front evaporator.
The actuation of the refrigerant compressor via the refrigerant compressor control valve depends mainly on the value of the evaporator temperature sensor, since the refrigerant pressure in the air conditioning changes as a function of the desired cooling in the front evaporator, and the refrigerant compressor has to increase or decrease the refrigerant supply by means of the refrigerant compressor control valve.
The actuation of the refrigerant compressor using the refrigerant compressor control valve is simultaneously placed as a message "KOMP_EIN" (refrigerant compressor switched on) on the Controller Area Network bus Class B (interior) (CAN-B). The EIS [EZS] control unit (N73) reads the message "KOMP_EIN" (refrigerant compressor switched on) and places it on the Controller Area Network bus Class C (engine compartment) (CAN-C).
The "KOMP_EIN" (Refrigerant compressor switched on) message is read in by the CDI control unit (N3/20), with engine 642, by the CDI control unit (N3/21), with engine 646, by the ME control unit (N3/29), with engine 271, or by the ME control unit (N3/23), with engine 272, via the CAN-C and used for the idle speed control.
At the same time, the message "KOMP_EIN" (refrigerant compressor switched on) is read in via CAN-C by the ETC [EGS] control unit (N15/3), with transmission 722.6, and used to correct the torque.
Inversely, the CDI control unit, with engine 646 or with engine 642, or the ME control unit, with engine 271 or with engine 272, transmits the message "KOMP_BAUS" (Switch off refrigerant compressor because of acceleration) or the message "KOMP_NOTAUS" (Emergency shutoff of refrigerant compressor) to the EZS control unit via the CAN-C.
The AAC [KLA] control and operating unit reads in the message "KOMP_BAUS" (switch off refrigerant compressor because of acceleration) from the EIS [EZS] control unit via CAN-B and reduces refrigerant delivery by the refrigerant compressor to 40 % by means of the refrigerant compressor control valve.
The AAC [KLA] control and operating unit reads in the message "KOMP_NOTAUS" (refrigerant compressor emergency switch-off) from the EIS [EZS] control unit via CAN-B and reduces refrigerant delivery by the refrigerant compressor to 2 % by means of the refrigerant compressor control valve.
With the "MAX cooling" function, the AAC [KLA] control and operating unit actuates the blend air flap actuator motor and the refrigerant compressor by means of the refrigerant compressor control valve. The blend air flap actuator motor fully opens the blend air and shutoff flap, so that the maximum air flow of the fresh or recirculated air blows by the front evaporator. The refrigerant compressor control valve actuates the refrigerant compressor at 100 %, so that it delivers the maximum amount of refrigerant and thus more refrigerant reaches the front evaporator.
Reheat mode (air dehumidification function)
It is possible to switch over to the reheat mode to prevent the windows from fogging up. Maximum cooling is supplied in the process and the temperature is then regulated according to the specified temperature set on the temperature selection switch. Reheat mode is activated or deactivated by actuating the reheat/ defrost mode button integrated in the AAC [KLA] control and operating unit.
The activation of reheat mode is indicated by illumination of the red LED in the reheat/defrost mode button. Following activation, the AAC [KLA] control and operating unit controls the refrigerant compressor at 100 % using the refrigerant compressor control valve so that the refrigerant compressor delivers the maximum amount of refrigerant and thus more refrigerant reaches the front evaporator. At the same time, the AAC [KLA] control and operating unit reads the interior temperature sensor and thus the current temperature in the vehicle interior.
Based on the specified temperature set on the temperature selection switch and the measured temperature in the vehicle interior, the AAC [KLA] control and operating unit controls the following components:
- Circulation pump
- Blend air flap actuator motor
- Air distribution actuator motor (M16/22)
In combination with the water pump, the circulation pump ensures circulation in the coolant circuit.
The blend air flap actuator motor adjusts the blend air and shutoff flap and the air distribution actuator motor adjusts the air distribution flap in order to control the air flow of the fresh or recirculated air which blows by the front heater heat exchanger. The blower motor is actuated with full power output by means of the blower regulator (M2n1), i.e. the blower motor runs in stage 4 in order to increase the air flow.
