w203 hvac

W203 & 463 HVAC
507 HVAC HO 203 & 463 (ACB ICC)
10-30-02
1
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.
2
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
3
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)
6
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.
11
Heater Box
Flap Actuator
Control
12
Flap Actuator Motors
C240 & G500 Utilizes 6 flap
actuator motors
C320 Utilizes 10 flap actuator motors
13
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
14
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.
16
Flap Motor Pin Identification
12v
Control Data
Ground
These four pins are used for coding
17
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
18
Color Coding Plugs on CAN-KLA
(+)
Signal
(-)
ACC (N22/7)
. .
..
. .
..
. .
..
19
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)
20
W203 Center Nozzle Function
6 = cold admix air wheel adds cold air to cabin mixture
Note: admix wheel control discontinued on MY2003
21
Cabin
Temperature
Regulation
22
W203 Auxiliary Coolant Pump (M13)
• Pump only operates
if cabin heating required
• Controlled through
front SAM (N10/1)
23
W203 Coolant Circuit Legend
1. Coolant pressure cap
with 2 stage valve
Aux. coolant pump
2. Expansion reservoir
3. Radiator
9
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
24
W203 Heater Box Airflow
Fresh or Recirc air--Cooled air-----------Heated air-----------Blended air-----------
25
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
28
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
31
Ambient Temperature Sensor (B14)
Used in conjunction with the 2 interior temperature sensors
for improved cabin temperature regulation.
32
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
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Refrigerant Pressure and Temperature
Sensor (B12/2)
•
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
35
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
36
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
37
Advanced
System
Functions
38
Tunnel Feature
C320 only
39
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
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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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