2006 MERCEDES-BENZ SPRINTER fuse

STANDARD PROCEDURE - LOW PRESSURE
FUEL PUMP TEST
NOTE: Assure fuel tank quantity and proper fuel
gauge operation. Assure that the fuel pump fuse or
relay is not open. Capture any fuel spillage and
store in appropriately marked containers.
NOTE: When the ignition switch is turned to the ON
position the fuel pump will begin to run for 20±30
seconds and then it stops.
The low pressure pump draws fuel out of the fuel
tank module and pushes the fuel towards the fuel fil-
ter. If the pressure reading is below specification,
look for damaged or leaking fuel lines or a restricted
fuel filter. If no problem is found with the fuel sys-
tem replace the low pressure fuel pump.
(1) Disconnect the negative battery cable.
(2) Connect a fuel gauge to the low pressure fuel
supply to the high pressure pump (Fig. 4).(3) Connect negative battery cable.
(4) Turn the ignition to the ON position and
observe the fuel gauge reading (Fig. 5).
(5) The fuel pressure should be 4.0 to 4.5 bar (58 -
65 psi) If the fuel pressure is below specification,
Fig. 3 WATER IN FUEL SENSOR
1 - WIF SENSOR
2 - WIF DRAIN
3 - FUEL FILTER
4 - FUEL SUPPLY FROM TANK
5 - FUEL SUPPLY TO HIGH PRESSURE PUMP
Fig. 4 FUEL GAUGE CONNECT AT HIGH PRESSURE
PUMP
1 - FUEL SUPPLY FITTING
2 - ADAPTOR
3 - FUEL GAUGE HOSE
4 - HIGH PRESSURE PUMP
5 - FUEL RETURN FITTING
Fig. 5 FUEL PRESSURE TEST AT HIGH PRESSURE
PUMP
14 - 4 FUEL SYSTEMVA

OPERATION - LOW PRESSURE PUMP
When the ignition switch is on, fused battery posi-
tive voltage is supplied to the electric lift pump,
which will run for 20±30 seconds and then stop. If
the engine is cranked, the pump will begin running
immediately supplying fuel through fuel filter and
onto the high pressure pump. The lift pump and low
pressure fuel circuit operate at a pressure between
3.8 -5.5 bar (55 - 80 psi.).
Fig. 7 PRODUCING HIGH PRESSURE
1 - FUEL SUPPLY TO PUMP 6 - PISTON
2 - VALVE 7 - PISTON SPRING
3 - VALVE SPRING 8 - CAM
4 - CHECK BALL 9 - ECCENTRIC SHAFT
5 - HIGH PRESSURE PASSAGE 10 - CIRCULAR PASSAGE
14 - 16 FUEL DELIVERYVA

At high temperatures, certain ceramic materials,
such as zirconium-dioxide (ZrO2) become oxygen ion
conductors. In a typical O2 sensor, the ZrO2 is used
as a solid electrolyte, which conducts oxygen ions.
The solid electrolyte is sandwiched between two plat-
inum electrodes. The sensor generates a small volt-
age when oxygen moves from the high concentration
side to the low concentration side.
The same hold true if the process is reversed. If
voltage is applied to the platinum electrodes, oxygen
can be pumped from one side of the solid electrolyte
to the other (from cathode to anode), becoming an
oxygen pump. The amount of current flow is directly
proportional to the amount of oxygen pumped by the
sensor. When the oxygen level on the supply side
reaches zero, the current stops.
The ECM activates the integral heater element to
raise the temperature of the sensor to 700C (192ÉF)
for the ZrO2 to become conductive. The heater ele-
ment is designed to reach this temperature within 8seconds and maintaining it at this level. In cold tem-
peratures, this can be delayed up to 5 minutes to
prevent damaging the ceramic coating of the sensor
from water condensation. Once the sensor is heated,
the exhaust gas components diffuse through the gas
sample chamber. Upon reaching the electrodes on the
oxygen pump and concentration cells they reach state
of thermodynamic balance (Fig. 26).
Fig. 25 O2 CONSTRUCTION
1 - EXHAUST PIPE 6 - REFERENCE AIR CHANNEL
2 - EXHAUST GAS FLOW 7 - HEATER ELEMENT
3 - O2 SENSOR CONNECTOR 8 - SENSOR CELL
4 - TRIMMING RESISTOR 9 - OXYGEN PUMP CELL
5 - GAS SAMPLE CHAMBER 10 - SAMPLE PASSAGE
14 - 46 FUEL INJECTIONVA

When the outside air contains smoke, odors, high
humidity, or if rapid cooling is desired, interior air
can by recirculated by selecting the Recirculation
Mode with the mode control knob. The mode control
knob operates the recirculation door through use of a
vacuum actuator. When the Recirculation Mode is
selected, the recirculation door is closed to prevent
outside air from entering the passenger compart-
ment.
To maintain minimum evaporator temperature and
prevent evaporator freezing, an evaporator tempera-
ture sensor is used.
The A/C system is designed for the use of non-CFC,
R-134a refrigerant only and uses an expansion valve
to meter refrigerant flow to the evaporator.
DIAGNOSIS AND TESTING
A / C PERFORMANCE
The A/C system is designed to provide the passen-
ger compartment with low temperature and low
humidity air. The A/C evaporator, located in the
HVAC housing is cooled to temperatures near the
freezing point. As warm damp air passes over the
fins of the A/C evaporator, the air transfers its heat
to the refrigerant in the evaporator coils and the
moisture in the air condenses on the evaporator fins.
During periods of high heat and humidity, an A/C
system will be more effective in the Recirculation
mode (max-A/C). With the system in the Recircula-
tion mode, only air from the passenger compartment
passes through the A/C evaporator. As the passenger
compartment air dehumidifies, the A/C system per-
formance levels rise.
Humidity has an important bearing on the temper-
ature of the air delivered to the interior of the vehi-
cle. It is important to understand the effect that
humidity has on the performance of the A/C system.
When humidity is high, the A/C evaporator has to
perform a double duty. It must lower the air temper-
ature, and it must lower the temperature of the
moisture in the air that condenses on the evaporator
fins. Condensing the moisture in the air transfers
heat energy into the evaporator fins and coils. This
reduces the amount of heat the A/C evaporator can
absorb from the air. High humidity greatly reduces
the ability of the A/C evaporator to lower the temper-
ature of the air.
However, evaporator capacity used to reduce the
amount of moisture in the air is not wasted. Wring-
ing some of the moisture out of the air entering the
vehicle adds to the comfort of the passengers.
Although, an owner may expect too much from their
A/C system on humid days. A performance test is the
best way to determine whether the system is per-
forming up to design standards. This test also pro-
vides valuable clues as to the possible cause oftrouble with the A/C system. The ambient air tem-
perature in the location where the vehicle will be
tested must be a minimum of 21É C (70É F) for this
test.
A / C PERFORMANCE TEST
WARNING: Refer to the applicable warnings and
cautions for this system before performing the fol-
lowing operation (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - WARNINGS) and (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
CAUTIONS). Failure to follow the warnings and cau-
tions could result in possible personal injury or
death.
NOTE: Very specific instructions and conditions
pertain to this procedure which are significantly dif-
ferent than procedures used in other vehicle appli-
cations. Follow each step in the order they are
presented. Do not skip steps or change conditions
from those stated or results will be adversely
affected and invalid.
NOTE: When connecting the service equipment
coupling to the line fitting, verify that the valve of
the coupling is fully closed. This will reduce the
amount of effort required to make the connection.
(1) Check for diagnostic trouble codes using a
DRBIIItscan tool. If no DTCs are found in the
engine control module (ECM), go to Step 2. If any
DTCs are found, repair as required, then proceed to
Step 2.
(2) Place the vehicle in the shade and operate the
heating-A/C system under the following conditions.
²Engine at idle at operating temperature
²All doors or windows open
²Transaxle in Neutral
²All A/C duct louvers open
²A/C-heater controls set to fresh air (NOT Recir-
culate), full cool, panel mode, high blower and with
A/C compressor engaged.
NOTE: The A/C compressor clutch is de-energized
under any of the following conditions:
²Restricted compressor (thermal fuse in the pul-
ley)
²Low pressure in the system
²Low evaporator temperature
²Hard acceleration (WOT)
²High coolant temperatures
(3) Insert a thermometer in the driver side center
panel air outlet and operate the A/C system until the
thermometer temperature stabilizes.
VAHEATING & AIR CONDITIONING 24 - 3

(4) With the A/C compressor clutch engaged, duct
temperature should not be less than 2É C (35É F) or
more than 12É C (54É F). The compressor clutch may
cycle, depending upon the ambient temperature and
humidity. If the clutch cycles, use the readings
obtained before the clutch disengaged.
(5) If the A/C compressor clutch has not cycled off
and the duct temperature is less than 2É C (35É F),
check the evaporator temperature sensor and circuitby performing the ATC Function Test (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - ATC FUNCTION TEST).
(6) If the air outlet temperature fails to meet the
specifications, refer to the A/C System Diagnosis
chart.
A/C SYSTEM DIAGNOSIS
Condition Possible Causes Correction
Rapid A/C compressor clutch
cycling (ten or more cycles
per minute).Very low refrigerant system
charge.See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
Equal pressures, but the
compressor clutch does not
engage.1. No refrigerant in the refrig-
erant system.1. See Refrigerant System Leaks in this
group. Test the refrigerant system for leaks.
Repair, evacuate and charge the refrigerant
system, if required.
2. Faulty fuse. 2. Check the fuses in the Power distribution
block and junction block. Repair the shorted
circuit or component and replace the fuses, if
required. Refer to Group 8.
3. Faulty A/C compressor
clutch coil.3. See A/C Compressor Clutch Coil in this
group. Test the compressor clutch coil and
replace, if required.
4. Improperly installed or faulty
evaporator temperature sensor.4. See Evaporator Temperature Sensor in this
group. Test the sensor and replace, if re-
quired.
5. Faulty A/C pressure trans-
ducer.5. See A/C Pressure Transducer in this
group. Test the sensor and replace, if re-
quired.
6. Faulty engine Control Mod-
ule (ECM).6. Refer to Group 9 - Engine Electrical Diag-
nostics for testing of the ECM. Test the ECM
and replace, if required.
Normal pressures, but A/C
Performance Test air temper-
atures at center panel outlet
are too high.1. Excessive refrigerant oil in
system.1. See Refrigerant Oil Level in this group.
Recover the refrigerant from the refrigerant
system and inspect the refrigerant oil content.
Restore the refrigerant oil to the proper level,
if required.
2. Blend door cable improperly
installed or faulty.2. See Mode Door Cables in this group. In-
spect the cable for proper operation and re-
place, if required.
3. Blend-air door(s) inoperative
or sealing improperly.3. See HVAC Housing in this group. Inspect
the blend-air door(s) for proper operation and
sealing. Repair if required.
24 - 4 HEATING & AIR CONDITIONINGVA

OPERATION
The compressor clutch components provide the
means to engage and disengage the compressor from
the engine serpentine accessory drive belt. When the
clutch coil is energized, it magnetically draws the
clutch into contact with the pulley and drives the
compressor shaft. When the coil is not energized, the
pulley freewheels on the clutch hub bearing, which is
part of the pulley.
The compressor clutch engagement is controlled by
several components:
²A/C switch on the A/C-heater control panel
²Evaporator temperature sensor
²A/C pressure transducer
²Air temperature sensor
²CAN bus messages
The compressor clutch is de-energized under any of
the following conditions:
²Blocked compressor (thermal fuse in the pulley)
²Low pressure in the system
²Low evaporator temperature
²Hard acceleration (WOT)
²High coolant temperatures
STANDARD PROCEDURE
A / C COMPRESSOR CLUTCH AIR GAP
If a new clutch plate and/or clutch pulley are being
used, the air gap between the clutch plate and clutch
pulley must be checked using the following proce-
dure:
(1) Using feeler gauges, measure the air gap
between the clutch plate and the clutch pulley fric-
tion surfaces.
(2) If the air gap is not between specifications
(Refer to 24 - HEATING & AIR CONDITIONING -
SPECIFICATIONS), add or subtract shims until the
desired air gap is obtained.
NOTE: The shims may compress after tightening
the compressor shaft bolt. Check the air gap in four
or more places on the clutch plate to verify that the
air gap is still correct. Spin the clutch pulley before
making the final air gap check.
A / C COMPRESSOR CLUTCH BREAK - IN
After a new compressor clutch has been installed,
cycle the compressor clutch approximately twenty
times (five seconds on, then five seconds off). During
this procedure, set the heater-A/C control in the
Recirculation Mode, the A/C button in the on posi-
tion, the blower motor switch in the highest speed
position, and the engine speed at 1500 to 2000 rpm.
This procedure (burnishing) will seat the opposing
friction surfaces and provide a higher compressor
clutch torque capability.
REMOVAL
The refrigerant system can remain fully-charged
during compressor clutch, pulley, or coil replacement.
The compressor clutch can be serviced in the vehicle.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the serpentine drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(3) Disconnect the engine wire harness connector
for the compressor clutch coil from the clutch coil
wire harness connector on the top of the compressor.
(4) Remove the retainer securing the compressor
clutch coil lead on the top of the compressor.
(5) Remove the bolt that secures the compressor
clutch to the compressor shaft (Fig. 2). If necessary, a
band-type oil filter wrench or strap wrench can be
placed around the clutch plate to aid in bolt
removal.
Fig. 1 A/C Compressor Clutch
1 - BOLT
2 - CLUTCH PLATE
3 - PULLEY AND BEARING
4 - FIELD COIL
5 - SNAP RING
6 - SNAP RING
7 - SHIM (2)
VACONTROLS-FRONT 24 - 9

INSTALLATION
(1) Position the rear A/C condenser fan relay into
the proper receptacle of the relay block located in the
rear A/C evaporator housing.
(2) Align the A/C condenser fan relay terminals
with the terminal cavities in the relay block recepta-
cle and push down firmly on the relay until the ter-
minals are fully seated.
(3) Install the rear air filter (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION -
REAR/AIR FILTER - INSTALLATION).
(4) Reconnect the negative battery cable.
A / C CONTROL MODULE
DESCRIPTION
The rear A/C control module (Fig. 5) is connected
to the rear A/C blower motor switch, rear evaporative
temperature sensor, rear A/C temperature control
and the temperature sensor.
The rear A/C control module is located in the upper
left side of the rear A/C evaporator housing.
OPERATION
The rear A/C control module is supplied fused bat-
tery power through the rear blower switch. The con-
trol module receives input signals from the rear A/C
blower motor switch, rear A/C temperature control,
rear temperature sensor and the rear evaporator
temperature sensor when the front A/C switch is
turned on. The rear A/C control module uses the
Fig. 4 Rear A/C Condenser Fan Relay
1 - REAR A/C EVAPORATOR HOUSING
2 - BLOWER MOTOR RELAY K204
3 - BLOWER MOTOR RELAY K2034 - BLOWER MOTOR RELAY K201
5 - REAR CONDENSER FAN RELAY K205
6 - REAR COMPRESSOR RELAY K206
Fig. 5 Rear A/C Control Module
1 - REAR A/C CONTROL MODULE
2 - MOUNTING TABS
3 - WIRE HARNESS CONNECTOR
24 - 28 CONTROLS - REARVA

INSTALLATION
NOTE: Replacement of the PTFE thread sealing
tape is required anytime the rear A/C low pressure
switch is removed from the rear suction line line.
Failure to replace the sealing tape could result in a
rear refrigerant system leak.
(1) Remove the tape or plug from the rear suction
line fitting.
(2) Install PTFE thread sealing tape onto the rear
A/C low pressure switch and install the switch onto
the rear suction line. Tightened the A/C low pressure
switch to 10 N´m (88 in. lbs.).
(3) Connect the wiring harness connector to the
rear A/C low pressure switch.
(4) Install new insulating tape around the rear A/C
low pressure switch area.
(5) Reconnect the negative battery cable.
(6) Evacuate the rear refrigerant system (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING
- STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE).
(7) Charge the rear refrigerant system (Refer to 24
- HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE).
(8) Install the cover onto the rear A/C evaporator
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C EVAPORA-
TOR COVER-REAR - INSTALLATION).
BLOWER MOTOR RELAY
DESCRIPTION
The three rear blower motor relays used for the
rear A/C system are International Standards Organi-
zation (ISO)-type relays (Fig. 11). Relays conforming
to the ISO specifications have common physical
dimensions, current capacities, terminal functions
and patterns. The rear blower motor relays are elec-
tromechanical devices that switches fused battery
current directly to the rear blower motors. The rear
blower motor relays are energized when the relay
coils are provided battery current by the rear blower
motor switch (Refer to 24 - HEATING & AIR CON-
DITIONING/CONTROLS/BLOWER MOTOR
SWITCH - DESCRIPTION).
The rear blower motor relays are located in the
relay block in the rear A/C evaporator housing.
OPERATION
The three ISO-standard rear blower motor relays
are electromechanical switches that uses a low cur-
rent input from the rear blower motor switch to con-
trol the high current output to the rear blower
motors. The movable, common feed relay contact is
held against the fixed, normally closed relay contact
by spring pressure. When the electromagnetic relay
coil is energized, it draws the movable common feed
relay contact away from the fixed, normally closed
relay contact and, holds it against the fixed, normally
open relay contact. This action allows high current to
flow to the rear blower motors.
When the relay coil is de-energized, spring pres-
sure returns the movable relay contact back against
the fixed, normally closed contact point. The resistor
Fig. 10 Rear A/C Low Pressure Switch
1 - INSULATING TAPE
2 - REAR A/C EVAPORATOR HOUSING
3 - WIRE HARNESS CONNECTOR
4 - REAR A/C LOW PRESSURE SWITCH
5 - REAR SUCTION LINE FITTING
Fig. 11 Rear Blower Motor Relays
1 - STANDARD ISO RELAY
2 - TERMINAL PATTERN
VACONTROLS - REAR 24 - 33