MERCEDES-BENZ SPRINTER 2006 Service Manual

or diode is connected in parallel with the relay coil,
and helps to dissipate voltage spikes and electromag-
netic interference that can be generated as the elec-
tromagnetic field of the relay coil collapses.
The rear blower motor relay terminals are con-
nected to the vehicle electrical system through recep-
tacles in the relay block located in the rear A/C
evaporator housing.
The rear blower motor relays cannot be repaired
and, if faulty or damaged, they must be replaced.
Refer to the appropriate wiring information for diag-
nosis and testing of the ISO-standard relay and for
complete HVAC wiring diagrams.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the air filter from the rear A/C evapo-
rator housing (Refer to 24 - HEATING & AIR CON-
DITIONING/DISTRIBUTION - REAR/AIR FILTER -
REMOVAL).
(3) Reach up into the rear A/C evaporator housing
and remove the rear blower motor relays as neces-
sary from the relay block (Fig. 12).
24 - 34 CONTROLS - REARVA

INSTALLATION
(1) Position the rear blower motor relays into the
proper receptacle of the relay block located in the
rear A/C evaporator housing as necessary.
(2) Align the blower motor relay terminals with
the terminal cavities in the relay block receptacle
and push down firmly on the relay until the termi-
nals 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.
BLOWER MOTOR SWITCH
DESCRIPTION
The blower motor for the optional rear A/C system
is controlled by a three position rocker switch
mounted in the switch panel located on the instru-
ment panel (Fig. 13). The rear A/C blower motor
switch allows the selection of one of two blower
motor speeds and an Off position.
OPERATION
With the front A/C switch activated, the rear
blower motor speed can be selected by pressing the
rocker switch upwards (high speed) or downwards
(low speed). To turn the rear blower motor off, switch
the blower motor switch to the center position.
Depending on the blower motor switch position, a
blower motor speed command signal is sent to one of
the two blower motor relays. When activated, relay 1
sends power through an integral resistor within the
rear A/C control module and then to the blower
Fig. 12 Rear Blower Motor Relays
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. 13 Rear Air Conditioning Switch
VACONTROLS - REAR 24 - 35

motor, while relay 2 when activated, sends power
directly to the blower motor.
The rear blower motor switch cannot be repaired
and, if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING
REAR BLOWER MOTOR SWITCH
Before testing the rear blower motor switch, verify
that the front A/C system is functional by performing
the ATC Fuction Test using the DRBIIItscan tool.
Use a volt/ohmmeter to test the rear blower motor
switch. For circuit descriptions and diagrams, refer
to the appropriate wiring information. The wiring
information includes wiring diagrams, proper wire
and connector repair procedures, details of wire har-
ness routing and retention, connector pin-out infor-
mation and location views for the various wire
harness connectors, splices and grounds.
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to discharge
before performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the wire harness connector from the
rear blower motor switch.
(3) Check for continuity between terminal 10 and
terminals 1, 7 and 4 of the blower motor switch. In
all instances, there should be continuity.
NOTE: To check the switch's internal circuits, con-
nect the negative lead of the ohmmeter to terminal
10 and the positive ohmmeter lead to terminals 1, 7
and 4. To check the switch's integral light emitting
diodes, reverse the ohmmeter leads.
(4) Check for continuity between the rear blower
motor switch terminals 3 and 7 as you move the
blower motor switch to each of the two speed posi-
tions, and the Off position. There should be continu-
ity in only one blower motor switch speed position.
(5) Check for continuity between the rear blower
motor switch terminals 4 and 8 as you move the
blower motor switch to each of the two speed posi-
tions, and the Off position. There should be continu-ity in only the other blower motor switch speed
position.
(6) If OK, test and repair the rear blower motor
switch wire harness circuits. If not OK, replace the
faulty rear blower motor switch.
REMOVAL
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to discharge
before performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.
NOTE: The rear A/C blower motor switch is used on
vehicles with the optional rear A/C system.
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the accessory switch panel from the
instrument panel (Refer to 23 - BODY/INSTRU-
MENT PANEL/ACCESSORY SWITCH BEZEL -
REMOVAL).
(3) Disconnect the wire harness connector from the
rear A/C blower motor switch (Fig. 14).
(4) Disengage the retaining tabs and remove the
rear A/C blower motor switch from the accessory
switch panel.
24 - 36 CONTROLS - REARVA

INSTALLATION
(1) Install the rear A/C blower motor switch into
the accessory switch panel. Make sure the retaining
tabs are fully engaged.
(2) Connect the wire harness connector to the rear
A/C blower motor switch.
(3) Install the accessory switch panel (Refer to 23 -
BODY/INSTRUMENT PANEL/ACCESSORY
SWITCH BEZEL - INSTALLATION).
(4) Reconnect the negative battery cable.
EVAPORATOR TEMPERATURE
SENSOR
DESCRIPTION
The rear evaporator temperature sensor (Fig. 15) is
used to signal the rear A/C control module to cycle
the rear A/C clutch in order to control rear evapora-
tor temperature. Controlling the evaporator tempera-
ture prevents condensation on the evaporator fins
from freezing and obstructing rear A/C system air
flow.
The rear evaporator temperature sensor consists of
a probe and a switch unit. The probe, which is a Neg-
ative Temperature Coefficient (NTC) thermistor in a
capillary tube, is inserted between the rear evapora-
tor coil fins to monitor evaporator temperature. The
switch unit contains internal control logic that mon-
itors the input from the probe in order to switch an
internal transistor that controls the output signal to
the rear A/C control module.
The rear evaporator temperature sensor is located
in the rear A/C evaporator housing.
OPERATION
The rear evaporator temperature sensor signals
the rear A/C control module to cycle the rear A/C
clutch off if the rear evaporator temperature goes
below approximately 1.6É C (35É F). When the tem-
perature reaches above approximately 3.9É C (39É F),
the rear evaporator temperature sensor signals the
rear A/C control module to cycle the rear A/C clutch
back on.
The rear evaporator temperature sensor cannot be
adjusted or repaired. If faulty or damaged, it must be
replaced. Refer to the appropriate wiring information
for complete HVAC wiring diagrams.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the air filter from the rear A/C evapo-
rator housing (Refer to 24 - HEATING & AIR CON-
DITIONING/DISTRIBUTION - REAR/AIR FILTER -
REMOVAL).
(3) Reach up into the rear A/C evaporator housing
and disconnect the two wire harness connectors from
the rear evaporator temperature sensor (Fig. 16).
(4) Carefully remove the sensor probe from the
rear A/C evaporator.
(5) Remove the two screws that secure the rear
evaporator sensor to the rear A/C evaporator housing
and remove the sensor.
Fig. 14 Rear A/C Blower Motor Switch
1 - WIRE HARNESS CONNECTOR
2 - REAR A/C BLOWER MOTOR SWITCH
3 - ACCESSORY SWITCH PANEL
Fig. 15 Rear Evaporator Temperature Sensor
1 - SWITCH UNIT
2 - MOUNTING TAB (2)
3 - CAPILLARY TUBE
4 - WIRE CONNECTORS
VACONTROLS - REAR 24 - 37

INSTALLATION
(1) Position the rear evaporator temperature sen-
sor to the rear A/C evaporator housing.
(2) Install the two screws that secure the rear
evaporator temperature sensor to the rear A/C evap-
orator housing. Tighten the screws to 2 N´m (17 in.
lbs.).
(3) Install the sensor probe into the rear A/C evap-
orator.
(4) Connect the two wire harness connectors to the
rear evaporator temperature sensor.
(5) Install the rear air filter (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION -
REAR/AIR FILTER - INSTALLATION).
(6) Reconnect the negative battery cable.
TEMPERATURE CONTROL
DESCRIPTION
The temperature control for the optional rear A/C
system is a thumbwheel-type control mounted in the
switch panel on the instrument panel (Fig. 17). The
rear A/C temperature control allows the selection of
four temperature settings when the rear A/C blower
motor is activated.OPERATION
With the front A/C switch and rear blower motor
activated, the rear A/C output temperature can be
selected by rotating the thumbwheel control upwards
(increase cooling) or downwards (decrease cooling).
Depending on the rear A/C temperature control posi-
tion, a temperature command signal is sent to the
Fig. 16 Rear Evaporator Temperature Sensor
1 - REAR A/C EVAPORATOR HOUSING
2 - SCREWS (2)
3 - REAR EVAPORATOR SENSOR SWITCH UNIT4 - WIRE HARNESS CONNECTORS
5 - REAR EVAPORATOR SENSOR PROBE
Fig. 17 Rear A/C Temperature Control
24 - 38 CONTROLS - REARVA

rear A/C control module. The temperature of the cir-
culated internal air of the rear compartment is mea-
sured by a temperature sensor located in the rear
evaporator unit. The value of the temperature sensor
is compared in the rear A/C control module with an
adjusted value at the rear A/C temperature control.
The rear A/C temperature control cannot be
repaired and, if faulty or damaged, it must be
replaced.
DIAGNOSIS AND TESTING
REARA/CTEMPERATURE CONTROL
Before testing the rear A/C temperature control,
verify that the front A/C system is operating correctly
by performing the ATC Function Test using the
DRBIIItscan tool. Use a volt/ohmmeter to test the
control. For circuit descriptions and diagrams, refer
to the appropriate wiring information. The wiring
information includes wiring diagrams, proper wire
and connector repair procedures, details of wire har-
ness routing and retention, connector pin-out infor-
mation and location views for the various wire
harness connectors, splices and grounds.
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to discharge
before performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the wire harness connector from the
rear A/C temperature control.
(3) Check for continuity between terminal 9 and
terminals 3 and 5 of the A/C temperature control. In
all instances, there should be continuity.
NOTE: To check the switch's internal circuits, con-
nect the positive lead of the ohmmeter to terminal 9
and the negative lead to terminals 3 and 5. To
check the switches integral light emitting diode,
reverse the ohmmeter leads.
(4) Check for resistance between terminal 3 and 5
of the A/C temperature control as you move the con-
trol to each temperature position. Resistance should
be present and should change for each position.(5) If OK, test and repair the rear A/C tempera-
ture control wire harness circuits. If not OK, replace
the faulty rear A/C temperature control.
REMOVAL
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to discharge
before performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.
NOTE: The rear A/C temperature control is used
only on models with the optional rear A/C unit.
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the accessory switch panel from the
instrument panel (Refer to 23 - BODY/INSTRU-
MENT PANEL/ACCESSORY SWITCH BEZEL -
REMOVAL).
(3) Disconnect the wire harness connector from the
rear A/C temperature control (Fig. 18).
(4) Disengage the retaining tabs and remove the
rear A/C temperature control from the accessory
switch panel.
Fig. 18 Rear A/C Temperature Control
1 - WIRE HARNESS CONNECTOR
2 - REAR A/C TEMPERATURE CONTROL
3 - ACCESSORY SWITCH PANEL
VACONTROLS - REAR 24 - 39

INSTALLATION
(1) Install the rear A/C temperature control into
the accessory switch panel. Make sure the retaining
tabs are fully engaged.
(2) Connect the wire harness connector to the rear
A/C temperature control.
(3) Install the accessory switch panel (Refer to 23 -
BODY/INSTRUMENT PANEL/ACCESSORY
SWITCH BEZEL - INSTALLATION).
(4) Reconnect the negative battery cable.
TEMPERATURE SENSOR
DESCRIPTION
The rear temperature sensor (Fig. 19) provides an
air outlet temperature signal to the rear A/C control
module through a two-wire harness lead and connec-
tor.
The rear temperature sensor is located in the rear
A/C evaporator housing.
OPERATION
The rear A/C temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the rear A/C control module. The resis-
tance in the sensor changes as air temperature
changes. Based upon the resistance in the sensor, a
specific voltage on the temperature sensor signal cir-
cuit is returned to the rear A/C control module,
which is programmed to correspond to a specific tem-
perature.
The rear A/C temperature sensor cannot be
adjusted or repaired and, if faulty or damaged, it
must be replaced.
DIAGNOSIS AND TESTING
REAR TEMPERATURE SENSOR
(1) Disconnect and isolate the negative battery
cable.
(2) Disconnect the wire harness connector from the
rear temperature sensor.
(3) Measure the resistance of the rear temperature
sensor. At ±40É C (±40É F), the sensor resistance
should be approximatley 336 kilohms. At 55É C (131É
F), the sensor resistance is should be approximaytly
25 kilohms. The rear sensor resistance should read
between these two values.
(4) If OK, test and repair the rear temperature
sensor wire harness circuits. Refer to the appropriate
wiring information for rear temperature sensor cir-
cuit descriptions and for complete HVAC wiring dia-
grams. If not OK, replace the faulty temperature
sensor (Refer to 24 - HEATING & AIR CONDITION-
ING/CONTROLS - REAR/TEMPERATURE SENSOR
- REMOVAL).
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the air filter from the rear A/C evapo-
rator housing (Refer to 24 - HEATING & AIR CON-
DITIONING/DISTRIBUTION - REAR/AIR FILTER -
REMOVAL).
(3) Reach up into the rear A/C evaporator housing
and disconnect the wire harness connector from the
rear temperature sensor (Fig. 20).
(4) Carefully remove the rear temperature sensor
from the bracket.
Fig. 19 Rear Temperature Sensor
1 - REAR TEMPERATURE SENSOR
2 - WIRE HARNESS CONNECTOR
24 - 40 CONTROLS - REARVA

INSTALLATION
(1) Carefully install the rear temperature sensor
onto the bracket located in the rear A/C evaporator
housing.
(2) Connect the temperature sensor wire harness
connector.
(3) Connect the wire harness connector to the rear
temperature sensor.
(4) Install the rear air filter (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION -
REAR/AIR FILTER - INSTALLATION).
(5) Reconnect the negative battery cable.
SUPPRESSOR FILTER - REAR
BLOWER MOTOR
DESCRIPTION
The two interference suppression filters (Fig. 21)
for the two rear blower motors protects the rear A/C
control circuits and the vehicles electrical system
from voltage spikes which may be generated by the
two blower motors or the three rear blower motor
relays. The suppression filters also impede the prop-
agation of RF interference into the vehicles electrical
system by the rear blower motors to ensure interfer-
ence-free radio reception.
The rear blower motor suppression filters are
located near the rear blower motors in the rear A/Cevaporator housing.
OPERATION
The rear blower motor suppression filters provide
protection against transient interference signals or
similar interference to the electronic rear blower
motor circuits which can effect the performance of
Fig. 20 Rear Temperature Sensor
1 - REAR A/C EVAPORATOR HOUSING
2 - TEMPERATURE SENSOR3 - BRACKET
4 - WIRE HARNESS CONNECTOR
Fig. 21 Rear Blower Motor Suppression Filter
1 - REAR BLOWER MOTOR SUPPRESSION FILTER (2)
2 - WIRE CONNECTOR (TO BLOWER MOTOR)
3 - WIRE CONNECTOR (TO REAR A/C HARNESS)
4 - MOUNTING BRACKET
VACONTROLS - REAR 24 - 41

the rear A/C control module circuits and radio recep-
tion quality. The suppression filters for the rear
blower motors consist of capacitors and inductance
coils.
The rear blower motor suppression filters cannot
be repaired and, if faulty or damaged, they must be
replaced. Refer to the appropriate wiring information
for complete HVAC wiring diagrams.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the cover from the rear A/C evaporator
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C EVAPORA-
TOR COVER-REAR - REMOVAL).
(3) Disconnect the two wire harness connectors
from the rear blower motor suppression filter being
serviced (Fig. 22).
(4) Remove the screw that secures the each rear
blower motor suppression filter to the rear A/C evap-
orator housing and remove the suppression filters as
required.
24 - 42 CONTROLS - REARVA

INSTALLATION
(1) Position the rear blower motor suppression fil-
ter being serviced to the rear A/C evaporator hous-
ing.
(2) Install the screw that secures each rear blower
motor suppression filter to the rear A/C evaporator
housing. Tighten the screw(s) to 2 N´m (17 in. lbs.).
(3) Connect the two suppression filter wire har-
ness connectors.
(4) 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).
(5) Reconnect the negative battery cable.
SUPPRESSOR FILTER - REAR
CONDENSER FAN
DESCRIPTION
The interference suppression filter (Fig. 23) for the
rear A/C condenser fan protects the rear A/C control
circuits and the vehicles electrical system from volt-
age spikes which may be generated by the rear con-
denser fan motor or the rear condenser fan relay. The
suppression filter also impedes the propagation of RF
interference into the vehicles electrical system by therear condenser fan to ensure interference-free radio
reception.
The rear condenser fan suppression filter is located
in the rear A/C condenser housing near the rear con-
denser fan.
Fig. 22 Rear Blower Motor Suppression Filter ± LH shown, RH similar
1 - REAR A/C EVAPORATOR HOUSING
2 - SUPPRESSION FILTER WIRE CONNECTOR
3 - BLOWER MOTOR WIRE CONNECTOR4 - SCREW
5 - REAR BLOWER MOTOR SUPPRESSION FILTER (2)
VACONTROLS - REAR 24 - 43