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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 or updated 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 instructions when testing, diagnosing or making repair. Illustrations and descriptions in this training reference are based on preliminary information and may not correspond 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 part is not permitted without written authorization from Mercedes-Benz USA, LLC or its successors. Published by Mercedes-Benz USA, LLC Printed in U.S.A.

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

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

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Contents

System I.D. Ventilation

EIS - Key Memory

Sensors

Flap Motors Temperature Control 4

C240 & G500 Pushbutton Module AAC (N22)

Note: “EC” button symbol is replaced with “AC off” as of 2003 model 5

C320 Pushbutton Module C-AAC (N22/7)

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C320 Activated Charcoal Filters Not available on C240 & G500

Location: under passenger side dash 7

W203 Dust Filter

• Replaced every “B” service • Battery has a vent tube installed 8

463 Dust Filter

• Replaced every “B” service 9

Blower Motor (A32m1) and Regulator (A32n1) • C240 & G500, 12 manual settings + Automatic

• C320, 7 manual settings + Automatic

NOTE: Blower motor is switched off while cranking engine. 10

W203 Closed Loop Operation with Ignition Off With ignition switched off, the fresh air / recirculated air flap is positioned at 50% opening.

50%

This position allows cabin air to escape when closing the vehicle doors. 50% Reducing the effort needed to close the doors.

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Heater Box Flap Actuator Control

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Flap Actuator Motors C240 & G500 Utilizes 6 flap actuator motors

C320 Utilizes 10 flap actuator motors

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C240 & G500 Flap Actuator Motor Location M2/5 - Fresh air / recirculating air flap positioning motor M2/6 - Left blend air flap positioning motor M2/7 - Right blend air flap positioning motor M2/15 - Left and right footwell flaps positioning motor M2/16 - Left and right defroster flaps positioning motor P83.40-2192-06

M2/21 - Fresh air flap positioning motor

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C320 Flap Actuation Motor Location M2/5 - Fresh air / recirculating air flap positioning motor M2/6 - Left blend air flap positioning motor M2/7 - Right blend air flap positioning motor M2/8 - Left defroster flap positioning motor M2/9 - Right defroster flap positioning motor M2/10 - Left footwell flap positioning motor M2/11 - Right footwell flap positioning motor M2/19 - Left fresh air flap positioning motor A32m1 - Blower motor

A32m2 - Charcoal filter flap motor

M2/20 - Right fresh air flap positioning motor 15

Flap Actuator Motors Contains a integral logic printed circuit board.

• All W203, 463, 163, R230 & W211 electric flap motors are identical • All flap actuator motors are connected via a common 3 wire ribbon cable, called the CAN-KLA. • This cable is connected to the pushbutton control module.

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Flap Motor Pin Identification 12v Control Data Ground

These four pins are used for coding

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Flap Motor Coding Plastic bridges built into the connector plug act as spreaders forcing shorting pins apart. Since there are 4 pins up to 16 coding variations are available. Plastic bridges 4 pins

for coding

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Color Coding Plugs on CAN-KLA (+)

Signal (-)

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 controlled by adjusting wheel (2).

(2)

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W203 Center Nozzle Function

6 = cold admix air wheel adds cold air to cabin mixture Note: admix wheel control discontinued on MY2003

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Cabin Temperature Regulation

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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

Aux. coolant pump

2. Expansion reservoir 3. Radiator

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4. Coolant thermostat 5. Coolant pump 6. Heat exchanger 7. Windshield washer fluid reservoir 8. Heater core 9. Aux. coolant pump

• Duo-valves are not required for 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 26

Flap Design Changes

W220 Chassis Design (Single flap)

W203 Chassis Design (Multi-flap) - Quieter operation - Improved air blending 27

Refrigerant Circuit

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W203 Refrigerant Circuit Changes Hi side Low side

Refrigerant press./ temp sensor 29

W203 Receiver Dryer with Replaceable Element

Follow instructions in WIS before 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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Sensor Inputs

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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)

The two in-car temperature sensor values are averaged unless the outside temperature sensor (B14) is reading under 50°F, then only the N70b1 is used for cabin temperature regulation. An open sunroof in this case can cause excessive heating complaints due to cool air swirling around N70b1. C320 - N22b1

C240 - N22b1

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

•

Measures humidity, ambient temperature and calculates dew point value

•

Keeps cabin air from becoming excessively dry

•

These values are used for controlling the A/C compressor output

* C320 uses a multi-function sensor 34

Refrigerant Pressure and Temperature Sensor (B12/2)

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Refrigerant pressure (B12), and refrigerant temperature (B12/1) have been integrated into 1 sensor

•

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

B12/2 is located under the radiator

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Sun Sensor (B32/2) C320 Only 4 quadrant design as used on W220

Affects: C240 has a false plastic cover

• Temperature regulation • Blower speed • Air distribution

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C240 & G500

vs

C320

• Painted display panel

• LCD display / back lit switches

• 6 Flap actuator motors

• 10 Flap actuator motors

• Dew point sensor

• Multi-function sensor

• Single air direction control

• Independent air direction control • Illuminated dash vent controls • Sun position sensor • Activated charcoal filters

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Advanced System Functions

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Tunnel Feature C320 only

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W203 & 463 Defroster Changes • Defroster outlet temperature is influenced by pushbutton temperature settings

• Amount of air drying (dehumidify) is affected by humidity

• Air is delivered to footwell flaps for up to 30 sec. after engine is started then switched to windshield

• C320 blower operates at 80% output C240 blower operates at full speed Both can be overridden with manual switch 40

EIS Stored Climate Control Settings The following climate control settings are stored in EIS. The data is stored separately for key #1 and #2.

#1

#2 SmartKeys

C320:

C240: (if equipped with full electric seats)

Settings stored:

Settings stored:

• • • • • • •

• Automatic mode • A/C off switch (on/off)

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

EIS (N73)

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