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W203 & 463 HVAC

507 HVAC HO 203 & 463 (ACB ICC)10-30-02

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These technical training materials are current as of the date noted on the materials, and may be revised orupdated without notice. Always check for revised or updated information.

To help avoid personal injury to you or others, and to avoid damage to the vehicle on which you are working,you must always refer to the latest Mercedes-Benz Technical Publication and follow all pertinent instructionswhen testing, diagnosing or making repair.Illustrations and descriptions in this training reference are based on preliminary information and may notcorrespond to the final US version vehicles. Refer to the official introduction manual and WIS when available.Copyright Mercedes-Benz USA, LLC, 2002

Reproduction by any means or by any information storage and retrieval system or translation in whole or partis not permitted without written authorization from Mercedes-Benz USA, LLC or its successors.Published by Mercedes-Benz USA, LLCPrinted in U.S.A.

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Course Objectives

At the conclusion of this section, the technician will:

• Identify the climate control system used on W203 & 463

• Locate climate control components and serviceable items

• Describe the function of climate control systems and related components

• Demonstrate proficiency in operation of AAC and C-AAC by completing shop modules

This presentation builds upon the information already covered in the Systems Training 1 (507) W220 HVAC presentation.

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Contents

EIS - Key Memory

Ventilation

Temperature Control

Sensors

Flap Motors

System I.D.

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C240 & G500 Pushbutton Module AAC (N22)

Note: “EC” button symbol is replaced with “AC off” as of 2003 model

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C320 Pushbutton Module C-AAC (N22/7)

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C320 Activated Charcoal FiltersNot available on C240 & G500

Location: under passenger side dash

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W203 Dust Filter

• Replaced every “B” service

• Battery has a vent tube installed

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463 Dust Filter

• Replaced every “B” service

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Blower Motor (A32m1) and Regulator (A32n1)

• C240 & G500, 12 manual settings + Automatic

• C320, 7 manual settings + Automatic

NOTE: Blower motor is switched offwhile cranking engine.

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W203 Closed Loop Operation with Ignition Off

With ignition switched off,the fresh air / recirculatedair flap is positioned at50% opening.

This position allows cabin airto escape when closing thevehicle doors.

Reducing the effort needed toclose the doors.

50%

50%

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Heater BoxFlap Actuator

Control

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C240 & G500 Utilizes 6 flapactuator motors

C320 Utilizes 10 flap actuator motors

Flap Actuator Motors

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P83.40-2192-06

C240 & G500 Flap Actuator Motor Location

M2/5 - Fresh air / recirculating air flappositioning motor

M2/6 - Left blend air flappositioning motor

M2/7 - Right blend airflap positioning motor

M2/15 - Left and rightfootwell flaps positioningmotor

M2/16 - Left and rightdefroster flaps positioningmotor

M2/21 - Fresh air flappositioning motor

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C320 Flap Actuation Motor LocationM2/5 - Fresh air /recirculating air flappositioning motor

M2/6 - Left blend airflap positioning motor

M2/7 - Right blend airflap positioning motor

M2/8 - Left defrosterflap positioning motor

M2/9 - Right defrosterflap positioning motor

M2/10 - Left footwellflap positioning motor

M2/11 - Right footwellflap positioning motor

M2/19 - Left fresh airflap positioning motor

M2/20 - Right fresh airflap positioning motorA32m1 - Blower motor A32m2 - Charcoal filter flap motor

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• All flap actuator motors are connected via a common 3 wire ribboncable, called the CAN-KLA.

• This cable is connected to the pushbutton control module.

Flap Actuator Motors

• All W203, 463, 163, R230 & W211 electric flap motors are identical

Contains a integral logicprinted circuit board.

17These four pins are used for coding

12v

Control Data

Ground

Flap Motor Pin Identification

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4 pins for coding

Flap Motor Coding

Plastic bridges built into theconnector plug act as spreadersforcing shorting pins apart. Sincethere are 4 pins up to 16 codingvariations are available.

Plastic bridges

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Color Coding Plugs on CAN-KLASignal

. . .

(-)

(+)

. . .. . .ACC (N22/7)

. . .

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W203 Fresh Air Vent Function

• Bleeds air from center and side air vents. • Reduces drafts

Amount of bleed air controlledby adjusting wheel (2).

(2)

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6 = cold admix air wheel adds cold air to cabin mixture

W203 Center Nozzle Function

Note: admix wheel control discontinued on MY2003

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CabinTemperatureRegulation

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W203 Auxiliary Coolant Pump (M13)

• Pump only operates if cabin heating required

• Controlled through front SAM (N10/1)

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W203 Coolant Circuit Legend

1. Coolant pressure cap

with 2 stage valve

2. Expansion reservoir

3. Radiator

4. Coolant thermostat

5. Coolant pump

6. Heat exchanger

7. Windshield washer fluid reservoir8. Heater core9. Aux. coolant pump

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Aux. coolant pump

• Duo-valves are not requiredfor temperature regulation

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W203 Heater Box Airflow

Fresh or Recirc air---Cooled air------------Heated air------------Blended air-----------

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W203 & 463 Blend Air Flap Function(Temperature Regulation)

Blending mode Cooling mode

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Flap Design Changes

W220 Chassis Design(Single flap) W203 Chassis Design

(Multi-flap)

- Quieter operation- Improved air blending

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RefrigerantCircuit

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W203 Refrigerant Circuit Changes

Hi side

Low side

Refrigerant press./ temp sensor

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W203 Receiver Dryer with Replaceable Element

Follow instructions in WISbefore replacing element.

Note: Internal hex nut. Do not remove while system is still charged. Special tool to remove

203 589 00 10 00

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SensorInputs

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Ambient Temperature Sensor (B14)Used in conjunction with the 2 interior temperature sensors

for improved cabin temperature regulation.

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In-car Temperature Sensors(N70b1) and (N22b1)

C240 - N22b1

The two in-car temperature sensor values are averaged unless the outsidetemperature sensor (B14) is reading under 50°F, then only the N70b1 isused for cabin temperature regulation. An open sunroof in this case cancause excessive heating complaints due to cool air swirling around N70b1.

C320 - N22b1

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Dew Point Sensor (B31/2)(C240 & G500)

Function:

• Measures humidity, ambienttemperature and calculatesdew point value

• Keeps cabin air frombecoming excessively dry

• These values are used forcontrolling the A/Ccompressor output

* C320 uses a multi-function sensor

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Refrigerant Pressure and TemperatureSensor (B12/2)

B12/2 is located under the radiator

• Refrigerant pressure (B12), andrefrigerant temperature (B12/1)have been integrated into 1 sensor

• Discreet wired to left SAM (N10/1),signal sent via CAN to AACpushbutton module (N22)

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Sun Sensor (B32/2)

4 quadrant design as used on W220

Affects:

• Temperature regulation

• Blower speed

• Air distribution

C320 Only

C240 has a false plastic cover

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C240 & G500 vs C320

• Painted display panel

• 6 Flap actuator motors

• Dew point sensor

• Single air direction control

• LCD display / back lit switches

• 10 Flap actuator motors

• Multi-function sensor

• Independent air direction control

• Illuminated dash vent controls

• Sun position sensor

• Activated charcoal filters

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AdvancedAdvancedSystemSystem

FunctionsFunctions

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Tunnel FeatureC320 only

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• Defroster outlet temperature isinfluenced by pushbutton temperaturesettings

• Amount of air drying (dehumidify) isaffected by humidity

• Air is delivered to footwell flaps for upto 30 sec. after engine is started thenswitched to windshield

• C320 blower operates at 80% outputC240 blower operates at full speedBoth can be overridden with manualswitch

W203 & 463 Defroster Changes

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EIS Stored Climate Control Settings

EIS (N73)SmartKeys

The following climate controlsettings are stored in EIS. Thedata is stored separately for key#1 and #2.

C320:Settings stored:

• Automatic mode• A/C off switch (on/off)• Defroster switch• Manual air settings• Blower speed• Temperature setting• ACF switch on/off

C240: (if equipped with full electric seats)

Settings stored:

• Automatic mode

• A/C off switch (on/off)

#1 #2