Climate Control - Basic Knowledge -- 210 Chassis: Other Mercedes-Benz E-class W210/S210

Ventilation, function - GF83.10-P-2000A

MODEL 210

Scheme 136

Function

The ventilation system

1. keeps the windows from fogging up
2. provides fresh air for the passengers
3. helps achieve a uniform and pleasant temperature quickly in the passenger compartment.

In normal operation ventilation is supported by the blower (A32m1) when the vehicle is standing still or to increase the air flow.

Fresh air is sucked in through the air intake in the engine hood and through the fresh air flap into the heater housing. The air travels through the air ducts to the air outlets in the passenger compartment depending on the settings on the heater or A/C pushbutton control module (N18, N19, N22).

The air passes through the ventilation slots below the rear shelf into the trunk and exits from the vehicle through the rear nozzle.

In the recirculated air mode air is sucked out of the passenger compartment through the recirculated air flap by the blower (A32m1) and blown into the heater housing.

Air inlet, location/function GF83.10-P-2138A Air ducts, location/purpose/design GF83.10-P-2139A Blower, location/purpose/design/function GF83.10-P-2102A Blower regulator, location/purpose/ function GF83.10-P-2141A Dust filter, location/purpose/function GF83.10-P-2142A Rear ventilation, location/purpose/ function GF83.10-P-2143A Defroster nozzle, location/purpose/function GF83.10-P-2144A Center nozzle, location/purpose/function GF83.10-P-2149A Side nozzle, location/purpose/design/ function GF83.10-P-2108A Front footwell air outlet, location/ purpose/function GF83.10-P-2145A Rear footwell air outlet, location/purpose/function GF83.10-P-2146A Rear compartment nozzle, location/ purpose/function only with code 570, 954a and 955a GF83.10-P-2151A Stowage compartment ventilation nozzle, location/purpose/function only with code 570, 954a and 955a GF83.10-P-2147A Fresh air/recirculated air flap, location/ purpose/design/function GF83.20-P-2104A Blower switch, location/purpose/function except code 581a and 498 GF83.25-P-2104A Air distribution switch, location/purpose/function except code 581a and 498 GF83.25-P-2103A Blower pushbutton, location/purpose/ function only with code 581a and 498 GF83.40-P-2144A Air distribution pushbutton, location/ purpose/function only with code 581a and 498 GF83.40-P-2159A Recirculated air pushbutton, location/ purpose/function GF83.40-P-2145A Auto pushbutton, location/purpose/ function only with code 581a and 498 GF83.40-P-2147A Activated charcoal filter pushbutton, location/purpose/function only with code 581a and 498 GF83.40-P-2149A Heater housing, location/purpose/design/function except code 581a and 498 GF83.20-P-2103A Air conditioning housing, location/purpose/design/ function only with code 580, 581a and 498 GF83.30-P-2104A Smog sensor, location/purpose/function only with code 581a and 498 GF83.10-P-2152A Activated charcoal filter, location/purpose/function only with code 581a and 498 GF83.30-P-2118A Activated charcoal filter actuator motor, location/purpose/function only with code 581a and 498 GF83.30-P-2117A

Scheme 137

Vacuum system, function - GF83.10-P-2001A

MODEL 210

Illustration of automatic heater (HEAT) and air conditioning (Tempmatic)

Scheme 138

Illustration of air conditioning (automatic)

Scheme 139

Vacuum system for automatic heater (HEAT) and air conditioning (Tempmatic)

The vacuum system for the automatic heater (HEAT) and air conditioning (Tempmatic) serves for control of the fresh air/recirculated air flap.

Vacuum is present at the switchover valve (Y13) from the valve block (36). The switchover valve (Y13) can be opened by pressing the recirculated air button ( ) on the pushbutton control module (N18, N19), which actuates the fresh air/recirculated air flap (44)

Scheme 140

Vacuum system for automatic air conditioning (automatic A/C)

With automatic air conditioning (automatic A/C) all flaps (37-48) for air distribution are controlled by the vacuum system.

Vacuum is present at the switchover valve block (Y11) from the cockpit interface (35). The switchover valve block (Y11) switches to control the individual flaps (37-48) depending on the setting on the pushbutton control module (N22).

Switchover valve, location/purpose/function GF83.10-P-2155A Valve strip arrangement/task/function only in code 581a and 498 GF83.10-P-2153A Defroster nozzle vacuum element, location/purpose/design/function Only with codes 581a and 498 GF83.10-P-2116A Blend flap vacuum element, location/purpose/design/function Only with codes 581a and 498 GF83.10-P-2118A Footwell flap vacuum element, location/purpose/design/function Only with codes 581a and 498 GF83.10-P-2120A Low pressure element fresh air-/Circulating air flap arrangement/task/function GF83.10-P-2159A Diverter flap vacuum element, location/purpose/design/function Only with codes 581a and 498 GF83.10-P-2123A

Blower, function - GF83.10-P-2102-02A

Function

The control voltage is switched to the blower regulator via the blower switch integrated into the automatic heater (HEAT)/air conditioning (Tempmatic) control module.

With AAC the air conditioning (AAC) control module compares the control voltage with a stored curve and switches it to the blower regulator which then actuates the blower. Manual operation is possible in 7 stages.

Residual engine heat utilization

In the residual engine heat utilization mode the control voltage is switched to the air conditioning (AAC) control module via the REST button ( )

Scheme 141

The voltages specified in the table below are maximum values. Different values can be measured when the recirculated air mode is switched on or the filters are clogged.

The AAC blower control is influenced by the following parameters

1. AUTO/manual blower setting
2. Time characteristics
3. Control function (EC, defroster, air distribution)
4. Outdoor temperature
5. Mode status heating/cooling
6. Sun intensity (models 210 and 140 only)
7. Cooling water temperature
8. Vehicle speed
9. Position of fresh air/recirculated air flap
10. Position of activated charcoal filter flap (models 210 and 140 with activated charcoal filter only, code 306a)
11. Position of diverter flap
12. Circuit 15/circuit 15x

Blower regulator, function - GF83.10-P-2103-01A

Function

With AAC a control voltage (0-6V) is transmitted to the blower regulator via the blower knob ( ) or in the automatic mode via the AUTO button ( ) with the AAC pushbutton control module

Scheme 142

Depending on the control voltage it then controls the operating voltage for the blower, regulating the blower speed within the range of 0 - 100 %.

In the manual mode actuation is subdivided into 7 stages (segments). The possible control voltages for the air conditioning (AAC) are listed in the table below.

Blower regulator, function - GF83.10-P-2103-01C

Function

On vehicles with automatic heater or Tempmatic air conditioning, the blower switch, integrated into the pushbutton control module, has 5 stages.

The control voltages are specified in the table below.

Dust filter, function - GF83.10-P-2104-02A

Function

The filter cartridge in the dust filter consists of a mat which purifies the air as it flows through.

The dust filter filters out 80 % of all particles up to a size 0.3 μ and 100 % of all pollen and particles with a size of 0.5 μ and larger.

On model 140 with activated charcoal filter, the dust filter is additionally coated with activated charcoal

Rear vent, function - GF83.10-P-2105-01A

Function

Louvers in the rear vent open as a result of the pressure from the air flowing through the vehicle allowing it to flow out.

If a vacuum is present in the vehicle due to a window or the sliding roof being open while driving, the louvers close automatically from the force of gravity. This prevents exhaust gases, dust and moisture from being sucked in.

Center nozzle, function - GF83.10-P-2107-01A

Illustrated on model 210

Function

The center nozzle (1) can be partially opened and closed with the adjustment wheel (2).

The direction of the air can be adjusted as desired upward, downward, to the left, right or to the middle with two separately adjustable louvers (3, 4).

On vehicles equipped with automatic heater (HEAT) fresh air exits from the center nozzle (1), on vehicles with air conditioning (Tempmatic) and automatic air conditioning (Auto A/C) blended air exits from the center nozzle (1).

Scheme 143

Side nozzle, function - GF83.10-P-2108-01A

Function

The direction of the air coming from the air outlet for ventilation of the side windows (4) cannot be adjusted, however, the outlet can be opened and closed with the adjustment wheel (2).

Adjustable louvers (3) in the lower air outlet allow the direction of the air to be adjusted upward, downward, to the left or right as desired.

The outlet can be opened and closed completely or partially with the adjustment wheel (2). Blended air exits from the side nozzle (1).

Scheme 144

Front footwell air outlet, function - GF83.10-P-2109-01A

Function

The air supply to the footwell air outlet can be opened and closed with the pushbutton control module (N18, N19, N22). There is no separate adjustment possibility. Blended air exits from the air outlet at the front footwell.

Rear footwell air outlet, function - GF83.10-P-2110-01A

Function

The air supply to the rear footwell air outlet can be opened and closed with the pushbutton control module.

There is not separate adjustment possibility. Blended air exits from the rear footwell air outlet.

When the rear air conditioning is switched on, the air flows from the rear A/C housing to the rear footwell air outlet.

Rear compartment nozzle, function - GF83.10-P-2111-01A

Function

The air direction can be adjusted upward, downward, to the left and right with the adjustment lever (2) for the two separately adjustable louvers (3, 4). The rear compartment nozzle (1) can be opened and closed with the control wheel (2).

Blended air exits from the rear compartment nozzle (1).

Scheme 145

Stowage compartment ventilation nozzle, function - GF83.10-P-2112-01A

Function

The air supply to the stowage compartment ventilation nozzle (1) can be opened and closed with the shut-off lever (2).

The air temperature corresponds approximately to that of the air exiting from the center nozzle. It cannot be adjusted separately.

The air supplied depends on

Scheme 146

1. the position of the blower switch.
2. the position of the air distributions switch.
3. the number of air outlets open.

Switchover valve, function - GF83.10-P-2115-01A

Function

The switchover valve (Y13) is controlled by the pushbutton control module (N18, N19). When power is present the solenoid valve opens actuating the vacuum element for the fresh air/recirculated air flap.

Fresh/recirculated air flap vacuum element, function - GF83.10-P-2122-01A

Function, automatic heater (HEAT) and air conditioning (Tempmatic)

When the button is pressed on the pushbutton control module (N18, N19) the switchover valve (Y13) is actuated. This puts the vacuum element for the fresh/recirculated air flap (44) under vacuum. In the recirculated air mode the recirculated air flap is open and the fresh air flap is closed

In the fresh air mode the fresh air flap is open and the recirculated air flap closed.

Scheme 147

Function, automatic air conditioning (automatic A/C)

When the button is pressed on the pushbutton control module (N22) the fresh/recirculated air switchover valve in the switchover valve block (Y11) is actuated putting the fresh/recirculated air flap vacuum element (44) under vacuum

In the recirculated air mode the recirculated air flap is open and the fresh air flap closed. In the fresh air mode the fresh air flap is open and the recirculated air flap closed.

On vehicles with automatic air conditioning it is possible to open the recirculated air flap 80 % or 100 %.

Scheme 148

Heating circuit, function - GF83.20-P-2003A

MODEL 210

Scheme 149

Function

The coolant pump (5) pumps cold coolant through the engine (M). Here the coolant absorbs the engine heat and is warmed up. Then the heated coolant flows through the heater core (8) where the heat is transferred to the passenger compartment air. The quantity of coolant flowing through the heater core (8) is controlled by the duovalve (Y21). The quantity of coolant can be regulated separately for left and right sides.

The coolant then travels through the coolant return (A) to the coolant pump (5). A coolant circulation pump may be installed in the return between the duovalve and coolant pump. The major portion of the coolant flows through the engine (M) rather than through the heater to the thermostat (4). The thermostat allows water to flow through the radiator (3) or directly back to the coolant pump (5) depending on the water temperature.

Duovalve, function - GF83.20-P-2100-01A

Function

When the temperature dial is set to "MIN" the pushbutton control module switches the duovalve solenoid (Y21) to ground, the solenoid pulls in and blocks the coolant flow through the heater core separately on the left and right sides.

If the temperature dial is set to "MAX" the pushbutton control module interrupts the ground connection, current does not flow through the solenoid and the maximum quantity of coolant flows through the heater core.

In normal operation the pushbutton control module switches the ground connection intermittently.

The locking and closing times of the duovalve (Y1) are subject to deviations between the actual temperature and set temperature.

Residual engine heat utilization

In the residual engine heat utilization mode the interior temperature is controlled in the same manner as while driving; the coolant is circulated by the coolant circulation pump (M13).

Heater core, function - GF83.20-P-2101-01A

Function

The heated coolant flows through the heater core. The aluminum tube banks and louvers pass the heat to the outside.

This heats up the air flowing through and exiting through the various defroster, ventilation and heating nozzles in the passenger compartment.

Coolant circulation pump, function - GF83.20-P-2102-01A

Function in heating mode

The quantity of coolant pumped to the heater core with the engine running depends on the coolant pump. The coolant circulation pump ensures that the water flows through the heater core uniformly without bubbles even at low speeds.

The coolant circulation pump is controlled by the pushbutton control module.

Function with residual engine heat utilization

The coolant circulation pump pumps the heated coolant to the heater core when the engine is standing still. When the REST button is pressed the temperature is controlled by the pushbutton control module (in the same manner as when the ignition is ON). The pushbutton control module switches the electric motor for the coolant circulation pump which drives the impeller via a magnetic clutch.

Heater housing, function - GF83.20-P-2103-02A

Normal operation of automatic heater (HEAT)

Scheme 150

Normal operation of automatic heater (HEAT) Function

During normal operation fresh air is sucked through the fresh air flap (1) or in the recirculated air mode air from the passenger compartment is sucked through the recirculated air flap (2) by the blower (21). After purification in the dust filter (20) the air travels through the unheated heater core (24) to the air outlets (7, 8, 9, 10 and 11).

At the air outlet (6) the unheated air flows out. In this mode only leakage air exits from the defroster nozzle (7a).

Heater housing, function - GF83.20-P-2103-02B

Heating mode for automatic heater (HEAT)

Scheme 151

Heating mode for automatic heater (HEAT) Function

In the heating mode fresh air is sucked through the fresh air flap (1) or in the recirculated air mode air from the passenger compartment is sucked through the recirculated air flap (2) by the blower (21). After purification by the dust filter (20) the air travels through the heater core (24).

The air is heated in the heater core (24) and flows to the air outlets (7, 8, 9, 10 and 11). Fresh air from outside exits from the air outlet (6). In this mode only leakage air exits from the defroster nozzle (7a).

Heater housing, purpose - GF83.20-P-2103-03A

The heater housing serves for holding the following components

1. Air guide flaps (1 to 11)
2. Dust filter (20)
3. Blower with blower control (21)
4. Heater core (24)
5. Vacuum elements

forming one complete unit.

The heater housing provides for distribution of the air required for ventilation of the vehicle to the appropriate air ducts and air outlets depending on the desired temperature in the passenger compartment.

The air guidance depends on various operating states such as

Scheme 152

1. Normal operation
2. Heating

Automatic heater (HEAT), function - GF83.25-P-0001A

MODEL 210

Function

The electronically controlled heating and ventilation system in the automatic heater maintains the desired passenger compartment temperature constant.

The heater core temperature sensor (B10/1) measures the air temperature at the heater core while the in-car temperature sensor (B10/4) measures the temperature in the passenger compartment. The micro-processor in the pushbutton control module (N18) compares the different readings with the desired temperature set with the temperature dials.

The micro-processor then changes the heat setting or maintains the present setting as required.

The automatic heater is capable of keeping the selected passenger compartment temperature constant up to an outdoor temperature of approximately 15 °C.

Automatic heater pushbutton control module position/function - GF83.25-P-2000A

MODEL 210

Scheme 153

Shown on residual engine heat recirculation (Codes 450, 670)

Scheme 154

Function

The control and operating module (N18) is the centerpiece of the automatic heater (HEAT). It permits performance, of adjustments required by the driver, such as

1. Temperature by using the temperature selection wheels (1)
2. Air quantity by using the blower switch (2)
3. Air distribution by using the air distribution switch (3)
4. Recirculated air by pressing the recirculated air pushbutton (4)
5. Activation of the residual engine heat recirculation, with ignition turned off, by pressing the Rest button (4) (special request)

Furthermore the control module integrated into the control and operation module (N18) takes over the comparison of specified / actual temperature values and adjustment of the preselected passenger compartment temperature.

The control and operation module (N18) can be diagnosed so that faults arising are stored in a fault memory, which the on board air conditioning system (DMNL Air conditioning 1.5) can be read out.

Blower switch Location/task/function GF83.25-P-2104A Air distribution switch Location/task/function GF83.25-P-2103A Temperature selection wheel Location/task/ function GF83.25-P-2105A Recirculated air pushbutton Location/task/function GF83.40-P-2145A Rest pushbutton Location/task/function with Code 450 and 670a only GF83.40-P-2148A

Blower switch, function - GF83.25-P-2100-02A

Function

The blower switch switches the control voltage for the blower regulator in five stages depending on the position via the pushbutton control module (N18, N19).

Air distribution switch, function - GF83.25-P-2101-01A

Function

The air distribution switch adjusts the air flaps using a cam for separate ventilation of the windshield and footwell.

The air distribution switch has 12 positions and can be turned 360°. The angle between the catch positions is 30°.

Temperature dial, function - GF83.25-P-2102-01A

Function

Turning the temperature dials adjusts a potentiometer. The potentiometer is thereby set to a particular resistance corresponding to the selected temperature and the pushbutton control module compares this setting with the temperature in the vehicle passenger compartment measured by the in-car temperature sensor.

The temperature dials allow the temperature for each side of the car to be set separately and infinitely between

"blue" = heater off and

"red" = max. heating.

When it is necessary to heat up the passenger compartment to the set temperature heat-up is accomplished as quickly as possible and then held constant.

Air conditioning (Tempmatic), interlinkage of components - GF83.30-P-0001-02B

Interlinkage of temperature control; Models 202, 208, 210

Scheme 155

Air conditioning (Tempmatic), interlinkage of components - GF83.30-P-0001-02F

Model 210

Model 210

Engines 104, 111, 602, 604, 605, 606 up to 8/96, Engine 119 up to 9/97

Scheme 156

Model 210 as of 9/96 up to 2/97

Engines 104, 602, 604, 605, 606

Scheme 157

Model 210 from 9/96 to 2/97

Engine 111

Scheme 158

Model 210

Engines 111, 611 as of 3/97

Engine 112 as of 6/98

Scheme 159

Model 210

Engines 113, 602, 604, 605, 606 as of 3/97

Engine 112 up to 5/98

Scheme 160

Air conditioning (Tempmatic), interlinkage of components - GF83.30-P-0001-02FA

Interlinkage of fan control; Model 210

Model 210

Engines 104, 111, 602, 604, 605, 606 up to 8/96

Engine 119 up to 9/97

Scheme 161

Model 210 as of 9/96 up to 2/97

Engines 104, 602, 604, 605, 606

Scheme 162

Model 210 as of 9/96 up to 2/97

Engine 111

Scheme 163

Model 210

Engines 111, 611 as of 3/97

Engine 112 as of 6/98

Model 210

Engines 113, 602, 604, 605, 606 as of 3/97

Engine 112 up to 5/98

Scheme 164

Air conditioning (Tempmatic), function - GF83.30-P-0001A

MODEL 210 with CODE (580) Air conditioning or Tempmatic for USA

Function

Electronically controlled coolant-, heating and ventilation system of tempmatic holds constant the desired interior temperature.

After start of engine, air conditioning system is always operational from blower speed 1 and works according to the so-called "Reheat" principle.

This means

Refrigerant compressor always runs when ambient temperature is above 1 °C and thereby cooling incoming air. This is primarily for comfort as cooling also has the effect of drying air which is an important prerequisite for a pleasant atmosphere. After the cooling process dried air on heater heat exchanger is heated to desired temperature, cooling system is shut off by pressing EC button.

heater mode

Heat exchanger temperature sensor (B10/1) measures air temperature on heater heat exchanger, while interior air temperature sensor (B10/4) determines current interior temperature.

In addition, ambient temperature is determined by ambient air temperature sensor (B14).

Microprocessor of control and operating unit (N19) compares the various measured values with the adjusted temperature on temperature dial and desired temperature.

Microprocessor regulates heater or holds current setting constant, as required.

Cooling mode

Evaporator temperature sensor (B10/6) measures temperature on evaporator air outlet, while interior air temperature sensor (B10/4) determines current interior temperature.

In addition, ambient temperature is determined by ambient air temperature sensor (B14).

Microprocessor of control and operating unit (N19) compares the various measured values with the adjusted temperature on temperature dial and desired temperature.

Microprocessor of air conditioning system adjusts or holds current setting constant, as required.

Dust filter replaced by combination filter BT83.10-P-0001-02F Auxiliary fan control unit replaced by new type Engine 104 from 09/96 up to 02/97 Engine 602, 604, 605, 606 as of 06/96 Engine 112 up to 05/98 Engine 113 as of 03/97 Engine 613 as of 07/99 BT83.40-P-0001-01F Control module, electric fan - engine/air conditioning system, replaced by new type Engine 111 except 111. 947 as of 09/96 Engine 111.947 as of 03/97 Engine 112 as of 06/98 Engine 611 as of 03/97 BT83.40-P-0001-04F Ventilation, function GF83.10-P-2000A Vacuum system, function GF83.10-P-2001A Heater circuit, function GF83.20-P-2003A Air conditioning (Tempmatic) (TAC), control and operating unit, function GF83.30-P-2000A Refrigerant circuit, function GF83.40-P-2001A Temperature control, function GF83.57-P-2000A Residual engine heat utilization, function with code 450, 670 GF83.75-P-2000A

Scheme 165

Tempmatic air conditioning pushbutton control module position/function - GF83.30-P-2000A

MODEL 210 with CODE (580) Air conditioning or Tempmatic for USA

Scheme 166

Shown on residual engine heat recirculation (Codes 450, 670)

Scheme 167

Function

The control and operating module (N19) automatic heater (HEAT) permits performance of adjustments required by the driver, such as

1. Temperature by using the temperature selection wheels (1)
2. Air quantity by using the blower switch (2)
3. Air distribution by using the air distribution switch (3)
4. Recirculated air by pressing the recirculated air pushbutton (4)
5. Activation of the residual engine heat recirculation, with ignition turned off, by pressing the Rest button (4) with Codes 450, 670
6. Switching off the cooling by pressing the EC pushbutton (5)

Furthermore the control module integrated into the control and operating (N19) module takes over regulation and control of systems, such as

1. comparison of the preselected / actual temperatures and adjustment of the air output temperature to the air outlets
2. automatic switching from fresh air to recirculated air
3. electrical actuation of the refrigerant compressor
4. actuation of the auxiliary ventilator

The control and operation module (N19) can be diagnosed so that faults arising are stored in a fault memory, which can be read out with the aid of the Hand-Held-Tester.

When changing the control and operating module (N19) a variant coding should be performed with the aid of the Hand-Held Tester.

Blower switch Location/task/function GF83.25-P-2104A Air distribution switch Location/task/function GF83.25-P-2103A Temperature selection wheel Location/task/function GF83.25-P-2105A Recirculated air pushbutton Location/task/function GF83.40-P-2145A EC pushbutton Location/task/function GF83.40-P-2146A Rest pushbutton Location/task/function Special request GF83.40-P-2148A

Air conditioning housing, function - GF83.30-P-2104-02A

Normal operation, air conditioning (Tempmatic)

Scheme 168

Normal operation air conditioning (Tempmatic) Function

In the normal mode with the air conditioner switched off ( burning) fresh air is sucked in through the fresh air flap (1) or, in the recirculated air mode, air from the passenger compartment is sucked in through the recirculated air flap (2) by the blower (21). After purification in the dust filter (20) the air travels through the uncooled evaporator (23)

The air then flows through the unheated heater core (24) to the air outlets (6, 7, 8, 9, 10 and 11).

Air conditioning housing, function - GF83.30-P-2104-02B

Cooling mode, air conditioning (Tempmatic)

Scheme 169

Cooling mode, air conditioning (Tempmatic) Function

In the cooling mode with the air conditioning switched on ( button not burning) fresh air is sucked in through the fresh air flap (1) or, in the recirculated air mode, air is sucked in from the passenger compartment through the recirculated air flap (2) by the blower (21). The air is purified as it passes through the dust filter (20) and travels through the cooled evaporator (23) where it is dried and cooled

The dry cool air then flows through the unheated heater core (24) to the air outlets (6, 7, 8, 9, 10 and 11).

Air conditioning housing, function - GF83.30-P-2104-02C

Heating mode, air conditioning (Tempmatic)

Scheme 170

Heating mode, air conditioning (Tempmatic) Function

In the heating mode with the air conditioning switched on ( not burning) fresh air is sucked in through the fresh air flap (1) or, in the recirculated air mode, air from the passenger compartment is sucked through the recirculated air flap (2) by the blower (21). The air is purified as it flows through the dust filter (20) and travels through the cooled evaporator (23) where it is dried and cooled

The dried, cooled air then flows through the heated heater core (24) where it is heated up and flows on to the air outlets (6, 7, 8, 9, 10 and 11).

A/C housing, purpose - GF83.30-P-2104-04A

The A/C housing serves for holding the following components

1. Air guide flaps (1 to 11)
2. Dust filter (20)
3. Blower with blower regulator (21)
4. Evaporator (23)
5. Heater core (24)
6. Expansion valve
7. Vacuum elements

forming one complete unit.

The A/C housing provides for distribution of the air required for ventilation of the vehicle to the appropriate air ducts and air outlets depending on the desired temperature in the passenger compartment.

The air guidance depends on various operating states such as

Scheme 171

1. Normal operation
2. A/C mode
3. Heating

Receiver/drier (Tempmatic A/C), function - GF83.30-P-2106-02A

Function

The liquefied refrigerant travels under pressure to the receiver/drier where it flows through a precious metal web to the filter block. The pores of the filter block are matched precisely to the molecular size of the refrigerant so that the refrigerant can flow through the filter block.

All other substances are filtered out and deposited on this molecular screen. The purified refrigerant flows through a riser pipe to the expansion valve.

An observation glass on the receiver/drier allows the fluid level to be checked.

Air conditioning (automatic), interlinkage of components - GF83.40-P-0001-02C

Model 210

Engines 104, 111, 602, 604, 605, 606 up to 8/96

Engine 119 up to 9/97

Scheme 172

Model 210 from 9/96 to 2/97

Engines 104, 602, 604, 605, 606

Scheme 173

Model 210 from 9/96 to 2/97

Engine 111

Scheme 174

Model 210

Engines 111, 611 as of 3/97

Engine 112 as of 6/98

Scheme 175

Model 210

Engines 113, 602, 604, 605, 606 as of 3/97

Engine 112 up to 5/98

Scheme 176

Automatic air conditioning (automatic A/C), interlinkage of components - GF83.40-P-0001-02FA

Interlinkage of fan control

Model 210

Model 210

Engines 104, 111, 602, 604, 605, 606 up to 8/96

Engine 119 up to 9/97

Scheme 177

Model 210 as of 9/96 up to 2/97

Engines 104, 602, 604, 605, 606

Scheme 178

Model 210 from 9/96 to 2/97

Engine 111

Scheme 179

Model 210

Engines 111, 611 as of 3/97

Engine 112 as of 6/98

Scheme 180

Model 210

Engines 113, 602, 604, 605, 606 as of 3/97

Engine 112 up to 5/98

Scheme 181

Automatic air conditioning (automatic A/C), interlinkage of components - GF83.40-P-0001-02FC

Interlinkage of temperature control; Model 210

Scheme 182

Automatic climate control (auto A/C), function - GF83.40-P-0001A

MODEL 210 with CODE (581a) Air conditioning (Automatic)

Function

Electronically controlled coolant-, heater and ventilation system of automatic climate control (auto A/C) holds constant the desired interior temperature.

Except +/ automatic climate control (auto A/C) is always operational +/ after start of engine and works according to the so-called "Reheat" principle. This means

Refrigerant compressor always runs when ambient temperature is above 1 °C and thereby cooling incoming air. This is primarily for comfort as cooling also has the effect of drying air which is an important prerequisite for a pleasant atmosphere. After the cooling process dried air on heater heat exchanger is heated to desired temperature.

Cooling system is shut off by pressing EC button.

In order to prevent misting up of windows, footwell flaps are fully opened for a period of 30 seconds after switching on ignition

heater mode

Heat exchanger temperature sensor (B10/1) measures air temperature on heater heat exchanger, while interior air temperature sensor (B10/4) determines current interior temperature.

In addition, ambient temperature is determined by ambient air temperature sensor (B14).

Microprocessor of control and operating unit (N22) compares the various measured values with temperature preselected on temperature buttons.

Microprocessor of automatic climate control (auto A/C) adjusts or holds current setting constant, as required.

Cooling mode

Evaporator temperature sensor (B10/6) measures temperature on evaporator air outlet, while interior air temperature sensor (B10/4) determines current interior temperature.

In addition ambient temperature is determined by ambient air temperature sensor (B14) and sunshine is determined via sun sensor (B32).

Microprocessor of control and operating unit (N22) compares the various measured values with temperature preselected on temperature buttons.

Microprocessor of automatic climate control (auto A/C) adjusts or holds current setting constant, as required.

Air quantity and air distribution are adjusted fully automatically via automatic switching.

Auxiliary fan control module replaced by new type Engine 104 from 09/96 up to 02/97 Engine 602, 604, 605, 606 as of 06/96 Engine 112 up to 05/98 Engine 113 as of 03/97 engine 613 as of 07/99 BT83.40-P-0001-01F Control module, electric fan - engine/air conditioning system, replaced by new type Engine 111 except 111. 947 as of 09/96 Engine 111.947 as of 03/97 Engine 112 as of 06/98 Engine 611 as of 03/97 BT83.40-P-0001-04F Air quality sensor replaced by new type BT83.40-P-0001-03F Ventilation, function GF83.10-P-2000A Vacuum system, function GF83.10-P-2001A Heater circuit, function GF83.20-P-2003A Automatic climate control (Auto A / C) control and operating unit GF83.40-P-2000A Refrigerant circuit, function GF83.40-P-2001A Temperature control, function GF83.57-P-2000A Residual engine heat utilization, function with code 450, 670 GF83.75-P-2000A

Automatic air conditioning pushbutton control module position/function - GF83.40-P-2000A

MODEL 210 with CODE (581a) Air conditioning (Automatic)

Scheme 183

Function

The control and operating module (N22) permits performance of adjustments required by the driver, such as

Scheme 184

Scheme 185

1. Passenger compartment temperature by pressing the warm/cold pushbuttons
2. Manual air quantity by pressing the pushbutton +/
3. Manual air distribution by pressing the pushbutton
4. Recirculated air by pressing the pushbutton
5. Activation of residual engine heat recirculation, with ignition off, by pressing the pushbutton
6. Switching off cooling by pressing the pushbutton
7. Automatic air distribution and blower speed by pressing the pushbutton
8. Defrosting function by pressing the pushbutton
9. Switching on the activated charcoal filter by pressing the pushbutton

The driver will be shown these adjustments on the display.

Furthermore the control module integrated into the control and operating (N22) module takes over regulation and control of systems, such as

1. comparison of the preselected / actual temperatures and adjustment of the passenger compartment temperature
2. automatic switching from fresh air to recirculated air
3. automatic air distribution
4. automatic blower speed
5. actuation of the refrigerant compressor
6. actuation of the auxiliary ventilator

The control and operation module (N22) can be diagnosed so that faults arising are stored in a fault memory, which can be read out onboard or with the aid of the Hand-Held Tester. (DMNL Air conditioning). When changing the control and operating module (N22) a variant coding should be performed with the aid of the Hand-Held Tester.

Refrigerant circuit, function - GF83.40-P-2001A

MODEL 210 with CODE (580) Air conditioning or, for USA, Tempmatic A/C with CODE (581a) Air conditioning (automatic) with CODE (498) Japanese version

Scheme 186

The A/C compressor (1) is driven by the engine and compresses the gaseous refrigerant, which is heated during this process and flows to the condenser (2).

The heat in the refrigerant resulting from compression is absorbed by the surface of the condenser (2). The refrigerant liquefies as it cools. As it flows through the receiver/drier (3) the refrigerant is purified of any chemical or mechanical impurities.

The expansion valve (4) sprays the cooled liquid refrigerant into the evaporator (5), which is located in the stream of fresh air. Here the refrigerant evaporates. This evaporation process absorbs heat from the fresh air flowing by on the outside through the tube and honeycomb system cooling the air.

The moisture entrained in the air condenses and is drained outside. The air is dried. The A/C compressor (1) sucks in the refrigerant which has become gaseous due to the heat absorbed and compresses it again.

Cooled air can be routed to various outlet openings in the passenger compartment with the engine running and blower switched on. The intensity of the cooling depends on the temperature set for the passenger compartment and the blower power.

Addition ventilator , location/purpose/function Engines 104/119/602/604/605 and 606 Engine 111 up to 08.96 Engine 113 as of 03.97 Engine 112 up to 05.98 Engine 613 as of 07.99 GF83.40-P-2162A Cycle module, location/purpose/function Engine 119 Engines 104/111/602/604/605/606 up to 08.96 GF83.40-P-2166A Auxiliary fan control module, location/purpose/function Engine 104 from 09/96 to 02/97 Engines 602/604/605 and 606 as of 09/96 Engine 113 as of 03.97 Engine 112 up to 05.98 Engine 613 as of 07.99 GF83.40-P-2163A Electric fan engine/AC, location/purpose/function Engine 111 except 111.947 as of 09.96 Engine 111.947 as of 03.97 Engine 611 as of 03.97 Engine 112 as of 06.98 GF83.40-P-2151A Electric fan engine/AC control module, location/purpose/function Engine 111 except 111.947 as of 09.96 Engine 111.947 as of 03.97 Engine 611 as of 03.97 Engine 112 as of 06.98 GF83.40-P-2167A Condenser, location/purpose/function GF83.40-P-2152A Evaporator, location/purpose/function GF83.40-P-2164A Receiver/drier (Tempmatic), location/purpose/function Only with code 580 GF83.30-P-2120A Receiver/drier, location/purpose/function Only with codes 581a and 498 GF83.40-P-2153A Expansion valve, location/purpose/design/function GF83.40-P-2123A Refrigerant temperature sensor, location/purpose/function Only with codes 581a and 498 GF83.40-P-2154A Air conditioning coolant temperature sensor, location/purpose/function GF83.40-P-2155A Refrigerant pressure sensor, location/purpose/function GF83.40-P-2156A A/C compressor, location/purpose/design/function GF83.55-P-2100A Electro-magnetic clutch, location/purpose/design/function GF83.55-P-2101A Evaporator temperature sensor, location/purpose/function GF83.57-P-2109A

Recirculated air button, function - GF83.40-P-2102-01A

Function with automatic heater (HEAT) and air conditioning (Tempmatic)

When the recirculated air button ( ) is pressed the electromagnetic fresh/recirculated air flap switchover valve is actuated for control of the recirculated air flap

Function with automatic air conditioning (automatic EC)

When the recirculated air button ( ) is pressed the electromagnetic fresh/recirculated air flap switchover valve block is actuated for control of the recirculated air flap

EC button, function - GF83.40-P-2103-01A

Function

When the button is pressed (LED comes on) the cooling mode is switched off. The A/C compressor is switched off by the pushbutton control module

The air is no longer cooled.

The quantity of air and air distribution are regulated automatically.

Auto pushbutton, function - GF83.40-P-2106-01A

Function

The automatic mode can be switched on by pressing the automatic pushbutton ( ). The automatic mode is indicated to the operator by the following display

1. The temperature values set for the left and right sides are displayed continuously
2. The blower symbol ( ) is displayed with the abbreviation AUTO for automatic

In the automatic mode the air quantity and air distribution functions are controlled automatically.

The defroster, footwell and blend flaps are controlled depending on the temperature measured by the heater core temperature sensors.

Exception

Control of the diverter flap is accomplished depending on the average deviation between the interior air temperature sensor and outdoor temperature.

REST button, function - GF83.40-P-2109-01A

Function

The residual engine heat utilization function can be switched on by pressing the residual engine heat utilization button ( ) on the pushbutton control module. The system then operates automatically in the following states

1. Passenger compartment temperature depending on setting on temperature dials and display
2. Blower low speed
3. Flap position permanently programmed
4. Battery voltage > 11.8 V
5. Time limitation 30 minutes or ignition ON

Auxiliary fan, function - GF83.40-P-2115-01A

Function

The auxiliary fan (M4) is switched on with infinite speed control depending on the refrigerant pressure and/or coolant temperature. The pushbutton control module (N19, N22) receives the coolant temperature from the ECT sensor (B11/4) and the refrigerant pressure from the refrigerant pressure sensor (B12) via the serial interface (K1) in the instrument cluster (A1). This input information is relayed on by the pushbutton control module (N19, N22) to the cycle module (N65) or the AIR control module (N65/1). Here the input information is compared with stored values and the auxiliary fan (M4) switched on if necessary.

Control of the auxiliary fan (M4) is accomplished as follows

1. Actuation on engines 104, 111, 602, 604, 605 and 606 from 09/95 to 08/96 and engine 119 is accomplished by the cycle module (N65).
2. Actuation on engines 104, 602, 604, 605 and 606 from 09/96 to 02/97 is accomplished by the AIR control module (N65/1)
3. Actuation on engines 113, 602, 604, 605 and 606 as of 03/97, engine 112 as of 05/98 and engine 613 as of 07/99 is accomplished by the signal acquisition and actuation module (N10/1) to the AIR control module (N65/1).

Cycle module, function - GF83.40-P-2116-01A

Function

The cycle module (N65) receives the current values for the coolant temperature and the refrigerant pressure via the pushbutton control module (N19, N22). The cycle module (N65) compares these values with stored values and switches on the auxiliary fan under the following conditions

1. Refrigerant pressure = 13 bar
2. Coolant temperature = 103 °C

The auxiliary fan (M4) is switched off under the following conditions

1. Refrigerant pressure = 12 bar
2. Coolant temperature = 100 °C

AIR control module, function - GF83.40-P-2117-01A

Function

The pushbutton control module controls the AIR control module (N65/1) with a minimum of 3 mA and max. 10 mA.

The AIR control module (N65/1) compares these values with stored values and switches on the auxiliary fan (M4) under the following conditions

1. Outdoor temperature = >5 °C
2. Refrigerant pressure = 13 bar
3. Coolant temperature = 103 °C
4. Limp-home mode (e.g. refrigerant pressure > 20 bar)

The auxiliary fan (M4) is switched off under the following conditions

1. Refrigerant pressure = 12 bar
2. Coolant temperature = 100 °C

Engine/AC electric suction fan, function - GF83.40-P-2118-01A

Function

The engine/AC electric suction fan (M4/3) operates at 20 % capacity for basic ventilation when the air conditioning is switched on. The fan speed is increased infinitely depending on the refrigerant pressure and/or coolant temperature.

The engine control module (N3) receives the refrigerant temperature from the coolant temperature sensor (B11/4) and the instrument cluster (A1) via the CAN bus and the serial interface (K2) for the AAC control module and the AAC pushbutton control module (N19, N22) receives the refrigerant pressure from the refrigerant pressure sensor (B12).

The input information is transmitted from the engine control module (N3) to the engine and air conditioning electric suction fan control module (N76).

There the input information is compared with stored values and the speed of the engine/AC electric suction fan (M4/3) increased if required.

Electric suction-type fan control module (engine/A/C), function - GF83.40-P-2119-01A

Function

The electric suction-type fan control module (engine/A/C) (N76) is controlled by the pushbutton control module (N19, N22).

The electric suction-type fan control module (engine/A/C) (N76) compares these values with the values stored and increases the speed of the electric suction-type fan (engine/A/C) (M4/3) from the basic ventilation speed of 20 % (with A/C compressor ON) infinitely up to 100 % under the following conditions

1. Refrigerant pressure = 13 bar
2. Coolant temperature = 103 °C

The speed is reduced to the basic ventilation speed of 20 % under the following conditions

1. Refrigerant pressure = 12 bar
2. Coolant temperature = 100 °C

Condenser, function - GF83.40-P-2120-01A

Function

The hot refrigerant is pressed into the condenser from above coming from the A/C compressor. Banks of tubes and louvers quickly absorb this heat. Exterior air is pressed or sucked through the condenser and heated up thereby cooling the refrigerant.

As the refrigerant is cooled down to a certain temperature dependent on the pressure, the refrigerant condenses and becomes liquid. The liquid refrigerant exits from the condenser at the bottom and flows into the receiver/drier.

Evaporator, function - GF83.40-P-2121-01A

Function

The liquid refrigerant is injected into the evaporator under high pressure. Evaporators from the manufacturers Behr and Valeo are installed.

Behr: Plate-type evaporator of brazed half-plates with corrugated fins (model 210).

Behr: Conventional layout consisting of banks of tubes and louvers (models 129, 140, 170, 202 and 208)

Valeo: Conventional layout consisting of banks of tubes and louvers The heat required for evaporation is absorbed from the air flowing past the evaporator cooling the air. The fins or louvers provide a large evaporator surface ensuring quicker heat exchange.

The moisture condensing out of the air as it cools is drained outside through condensed water drain hoses. In addition the solid particles are removed from the air by the condensing water purifying the air.

Expansion valve, function - GF83.40-P-2123-01A

Function

When the A/C compressor is switched on the pressure in the evaporator decreases causing the diaphragm (1) to flex downward in an arch. The tappet (3) follows the motion of the diaphragm and presses the valve ball (4) away from its seat against the force of the spring (5). The refrigerant is sprayed into the evaporator through the open valve.

Since the motion of the diaphragm (1) is dependent on the intake pressure as well as the temperature at the evaporator output, only the quantity of refrigerant which can be evaporated optimally is injected.

Scheme 187

ECT sensor, function - GF83.40-P-2125-01A

Function

The ECT sensor sends a resistance value corresponding to the coolant temperature via the instrument cluster and the serial interference (K1) to the pushbutton control module. Here the value is processed and the A/C compressor is switched off in two stages as follows

Stage 1

At a coolant temperature >123 °C the duty factor is reduced by 50 %. In this case the A/C compressor is switched on in cycles, i.e. off approx. 20 sec. and on approx. 20 sec.

If the coolant temperature drops to below 123 °C the A/C compressor is switched on again permanently.

Stage 2

At a coolant temperature >127 °C the A/C compressor is switched off completely.

When the coolant temperature drops to below 127 °C the A/C compressor is switched back on in the cycled mode (stage 1).

Refrigerant pressure sensor, function - GF83.40-P-2126-01A

Function

Switching off the A/C compressor

The refrigerant pressure sensor transfers the current value to the pushbutton control module. When the following values are present the A/C compressor is switched off by the pushbutton control module

1. Refrigerant pressure < 2 bar = A/C compressor off
2. Refrigerant pressure >28 bar = A/C compressor off

Switching on the auxiliary fan

The pressure measured by the refrigerant pressure sensor is also compared with a value stored in the pushbutton control module.

When the following values are present the fan is adjusted infinitely

1. Refrigerant pressure >16 bar = fan low speed
2. Refrigerant pressure >20 bar = fan maximum speed

Recirculating air pushbutton, position/task/function - GF83.40-P-2145A

MODEL 210

MODEL 140 up to 30.3.97 with CODE (498) Japanese version with CODE (350b) Information and Communication System (ICS)

MODEL 140 as of 1.4.97 with CODE (498) Japanese version

MODEL 202 up to 31.8.95 with CODE (305a) Dust filter with CODE (450) Taxi version with CODE (581a) Air conditioning (automatic)

MODEL 202 as of 1.9.95

MODEL 208

MODEL 170

Recirculating air pushbutton, position Model 210 GF83.40-P-2102-02A Model 210 and 140 Japanese version GF83.40-P-2102-02B Model 202 with Code 305a, 450 and 581a up to 31.08.95 GF83.40-P-2102-02C Model 202 as of 01.09.95 Model 208 except Code 581a GF83.40-P-2102-02E Model 208 with Code 581a GF83.40-P-2102-02K Model 170 GF83.40-P-2102-02G Recirculating air pushbutton, task The recirculating air pushbutton ( ) operates the fresh air/recirculated air flap. Recirculating air pushbutton, function GF83.40-P-2102-01A

Condenser position/task/function - GF83.40-P-2152A

MODEL 210 with CODE (580) Air conditioning or Tempmatic for USA with CODE (581a) Air conditioning (Automatic) with CODE (498) Japanese version

MODEL 140 as of 1.9.95

MODEL 202 with CODE (580) Air conditioning or Tempmatic for USA with CODE (581a) Air conditioning (Automatic)

MODEL 208 with CODE (580) Air conditioning or Tempmatic for USA with CODE (581a) Air conditioning (Automatic)

MODEL 170 with CODE (580) Air conditioning or Tempmatic for USA

MODEL 129 as of 1.6.96

Refrigerant compressor, function - GF83.55-P-2100-02A

Refrigerant compressor 7SB16C

Scheme 188

Function

After the electromagnetic clutch (A9k1) has produced the frictional connection between the automotive engine and the refrigerant compressor, the drive shaft (1) drives the swash plate (3). The rotation of the inclined swash plate (3) causes the pistons (4) to move in strokes. During the intake stroke, refrigerant vapor is sucked in via the inlet valve (6).

If the piston (4) moves in the counter direction, it delivers the refrigerant vapor via the pressure control valve (7), with the vapor being compressed and heating up, into the refrigerant line to the capacitor. With refrigerant compressor, model 7SB16C, the refrigerant vapor acts on the control valve (8.1) in the refrigerant compressor for volume control.

Volume control in model 7SB16C

With a low engine speed, the efficiency of an air conditioning system is severely reduced by the low number of working strokes of the refrigerant compressor and the reduced cooling of the refrigerant in the capacitor. In this situation there is an increase in the thermal load. The refrigerant compressor is therefore designed so that it has a sufficient delivery rate even at low rotational speeds.

With an increase in the engine speed and the vehicle speed, the thermal load drops and the delivery rate of the refrigerant compressor increases. To prevent the refrigerant compressor now from consuming unnecessary engine power and nevertheless to maintain the refrigeration cycle, the refrigerant compressor reduces its power from a maximum of 100 % to a minimum of 5 %.

Scheme 189

Function

100% power (I)

The conditions for full power are either a constantly low rotational speed or a high thermal load or both. The high manifold air pressure C causes the control valve to close. This prevents steam from flowing between the rear opening and the crankcase. There is always some flow through the transfer duct between the crankcase and the inlet opening. Therefore, in the crankcase there is almost the same pressure B as on the inlet side C . As a result, the swash plate is moved into the position for maximum volume. The angle between the swash plate and the vertical is at its greatest. This results in a large stroke.

Power from 100% to 5% output ( II)

If the influencing conditions change in that the thermal load drops or the engine speed increases, the pressure on the inlet side C drops and allows the control valve to open.

Then compressed refrigerant now flows from the rear opening to the crankcase. The pressure in the crankcase B increases therefore and causes the swash plate to reduce its angle, which leads to a reduction in power.

Scheme 190

Function

5% power (III)

If the engine speed is high or the thermal load is low, this results in a constantly low manifold air pressure C which keeps the control valve open.

There is a flow from the high-pressure side A to the crankcase. The pressure in the crankcase B reaches a peak. Consequently, the swash plate is forced into a position in which only a minimum power is possible. The angle between the vertical and the swash plate is at its smallest. This results in a small stroke.

Power from 5% to 100% output ( IV )

If the conditions change again in that the thermal load increases or the engine speed drops, the manifold air pressure C increases. There is now no longer any flow between the rear opening and the crankcase.

Due to the uniform flow from the crankcase to the inlet opening through the transfer duct, the high pressure A reaches almost the same level as the manifold air pressure C . Consequently, the swash plate angle increases and therefore the power increases until it reaches a maximum.

Electromagnetic clutch, function - GF83.55-P-2101-01A

Electromagnetic clutch (A9k1)

Scheme 191

Function

In order to start operating the refrigerant compressor, the pushbutton control module (N19, N22) actuates the electromagnetic clutch (A9k1) and the solenoid (5) is supplied with electrical current. The magnetic force attracts the pressure plate (6) against the rubber insert (7) and holds it securely. This creates the frictional connection between the automotive engine and the refrigerant compressor. If the solenoid (5) is de-energized, then the pressure plate (6) is pressed back by the rubber insert (7) into its rest position and the frictional connection is interrupted.

Safety shutoff of the refrigerant compressor

To prevent a mechanical defect in the refrigerant compressor from causing the poly V-belt to jump loose, the electromagnetic clutch releases itself automatically. With a mechanical defect, the refrigerant compressor rotates more sluggishly or even locks completely. The heat generated at the friction surface causes the melting fuse (2) in the solenoid (5) to melt. The current supply to the solenoid (5) is interrupted and the frictional connection is released.

Electromagnetic clutch, design - GF83.55-P-2101-03A

Electromagnetic clutch (A9k1)

The pulley (1) on the A/C compressor drive shaft (4) is driven by a poly-V-belt. It turns on the ball bearing (3) around the magnetic coil (5) fastened to the A/C compressor housing. The pressure plate (6) with rubber insert (7) is connected to the A/C compressor drive shaft (4) by splines (8) allowing it to move in the axial direction.

Scheme 192

Temperature control, function - GF83.57-P-2000A

MODEL 210

Function

The temperature set with the temperature dials (automatic heater and air conditioning (Tempmatic)) or the temperature buttons (automatic air conditioning) is achieved and held constant by

1. Heating the air in the heater core
2. Cooling the air in the evaporator
3. Cooling and reheating (reheat mode)

Heat-up

The heater core heats up the air as it flows through and travels on through the air ducts into the vehicle passenger compartment. The heat given up by the heater core is regulated by the flow rate of the hot coolant through the duovalve.

Control of the duovalve is accomplished by the pushbutton control module (N18, N19, N22).

Cooling (automatic heater)

Cooling is accomplished by closing the duovalve so that hot coolant cannot flow into the heater core.

Cooling (air conditioning (Tempmatic) and automatic air conditioning)

The liquid refrigerant under high pressure expands as it passes through the expansion valve into the evaporator reducing the pressure. The refrigerant then evaporates. The heat of evaporation required for this purpose is taken from the air flowing through the evaporator. The cooled air then travels through the air ducts into the vehicle passenger compartment.

Reheat mode (air conditioning (Tempmatic) and automatic air conditioning)

The air which has been cooled and dehumidified by the evaporator is heated up again in the heater core. This prevents the windows from fogging up on the inside.

Temperature dial, location/purpose/function GF83.25-P-2105A Warm temperature button, location/purpose/function Only with code 581a GF83.40-P-2160A Cold temperature button, location/purpose/function Only with code 581a GF83.40-P-2161A Duovalve, location/purpose/design/function GF83.20-P-2107A Heater core, location/purpose/function GF83.20-P-2108A Coolant circulation pump, location/purpose/function GF83.20-P-2109A Evaporator, location/purpose/function GF83.40-P-2164A Expansion valve, location/purpose/design/function GF83.40-P-2123A A/C compressor, location/purpose/design/function GF83.55-P-2100A In-car temperature sensor with aspirator blower, location/purpose/function GF83.57-P-2107A Heater core temperature sensor, location/purpose/function GF83.57-P-2108A Evaporator temperature sensor, location/purpose/function GF83.57-P-2109A Outside air temperature sensor, location/purpose/function GF83.57-P-2110A Sun sensor, location/purpose/function GF83.57-P-2111A

In-car temperature sensor with aspirator blower, function - GF83.57-P-2100-02A

Function

The in-car temperature sensor is equipped with an aspirator blower which continuously sucks air out of the vehicle passenger compartment for measurement of the temperature.

It is connected to the pushbutton control module by a separate electric lead.

The aspirator blower provides continuous circulation of the interior air around the in-car temperature sensor to ensure a high degree of control accuracy.

Heater core temperature sensor, function - GF83.57-P-2101-01A

Function

The heater core temperature sensor is a temperature dependent resistor. The resistance measured is relayed to the pushbutton control module. Here it is compared with the temperature set on the pushbutton control module. Each temperature setting is associated with a certain resistance.

The pushbutton control module determines the opening time for the duovalve by comparing the actual value and the stored value for the setting.

Evaporator temperature sensor, function - GF83.57-P-2102-02A

Function

The evaporator temperature sensor is located in the air flow behind the evaporator. It relays the resistance coinciding with the temperature at the evaporator to the pushbutton control module.

At an evaporator temperature of 1 to 3.5 °C the A/C compressor is switched off. This prevents the evaporator from icing up. This ensures that the outlet temperature at the nozzles deviates only slightly.

Outside air temperature sensor, function - GF83.57-P-2103-01A

Function

The resistance of the outside air temperature sensor depends on the ambient temperature and the speed. When the outdoor temperature increases the resistance decreases. This information is relayed via the instrument cluster and serial interface (K1) to the pushbutton control module.

This information causes a slight reduction or increase of the temperature set on the pushbutton control module.

This provides greater comfort by adapting the temperature to the temperature perceived subjectively by the passengers.

The interrelationship between the outdoor temperature and vehicle speed prevents an excessively high temperature from being relayed to the pushbutton control module, when the vehicle is standing still or driving slowly resulting from heat being radiated from the engine. The temperature measured last is used when the ignition is switched off and on and at speeds below 20 km/h.

Outside air temperature sensor arrangement - GF83.57-P-2103-02S

(Shown on model 220)

Scheme 193

Outside air temperature sensor position/task/function - GF83.57-P-2110A

MODEL 210 with CODE (580) Air conditioning or Tempmatic for USA with CODE (581a) Air conditioning (Automatic) with CODE (498) Japanese version

MODEL 140 as of 1.9.95

MODEL 202 with CODE (580) Air conditioning or Tempmatic for USA with CODE (581a) Air conditioning (Automatic)

MODEL 208 with CODE (580) Air conditioning or Tempmatic for USA with CODE (581a) Air conditioning (Automatic)

MODEL 170 with CODE (580) Air conditioning or Tempmatic for USA

MODEL 129 as of 1.6.96

Function of residual engine heat utilization - GF83.75-P-2000A

MODEL 210 with CODE (450) Taxi version with CODE (581a) Air conditioning (Automatic) with CODE (670a) Residual engine heat utilization (REST)

MODEL 210 as of 1.9.97 with CODE (580) Air conditioning or Tempmatic for USA

MODEL 140 as of 1.9.95

Function

Residual engine heat utilization with stationary ventilation allows vehicle to be heated even with ignition OFF . For this, system uses residual heat of engine and leads it via blower into interior. Residual engine heat utilization is put into operation by pressing rest button ( ) on control and operating unit

Heating water recirculation pump maintains water circuit to heater heat exchanger.

Air quantity is automatically adjusted.

With AAC, air distribution takes place automatically

1. Defroster nozzles leak air 80%
2. Footwell nozzles open 100%

Before switching on, ignition key must be turned to position 1 or 0 or withdrawn and rear nozzle must be closed.

Automatic switching off takes place

1. if key in steering wheel lock is turned to position 2
2. after approx. 30 minutes
3. if battery voltage falls below 11.5 V.