2006 MERCEDES-BENZ SPRINTER heating

IN - CAR TEMPERATURE SEN-
SOR
DESCRIPTION
The in-car temperature sensor measures the actual
air temperature within the passenger compartment.
The in-car temperature sensor is located inside of the
A/C-heater control behind a vented panel (Fig. 20)
and is not a separate serviceable component. The
A/C-heater control must be replaced if there is a fault
relating to the in-car temperature sensor.
OPERATION
Air from the passenger compartment flows over the
thermistor of the in-car temperature sensor. The
thermistor changes resistance with air temperature.
The ATC A/C-heater control measures this resistance
and calculates the temperature of the air. The A/C-
heater control then makes adjustments to maintain
the selected passenger compartment temperature.
The in-car temperature sensor cannot be adjusted
or repaired, and if faulty or damaged, the A/C-heater
control must be replaced (Refer to 24 - HEATING &
AIR CONDITIONING/CONTROLS/A/C HEATER
CONTROL - REMOVAL).
DIAGNOSIS AND TESTING
IN - CAR TEMPERATURE SENSOR
The in-car temperature sensor is diagnosed by per-
forming the ATC Function Test using the DRBIIIt
scan tool. Refer to Body Diagnostic Procedures. For
circuit descriptions and diagrams, refer to the appro-
priate wiring information.
MODE DOOR CABLES
REMOVAL
The air distribution control cables (mode door
cables) can be removed and installed without having
to remove the instrument panel from the vehicle.
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the center bezel from the instrument
panel (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL -
REMOVAL).
(3) Remove the A/C-heater control (Refer to 24 -
HEATING & AIR CONDITIONING/CONTROLS/A/C
HEATER CONTROL - REMOVAL).
(4) Mark and disconnect the control cables from
the A/C-heater control.
(5) Mark and disconnect the control cables from
the HVAC housing retainers (Fig. 21).
(6) Disconnect the control cables from the mode
door levers and remove the cables from the vehicle.
INSTALLATION
(1) Connect the two control cables to the mode
door levers (Fig. 22).
(2) Connect the two control cables to the A/C-
heater control.
NOTE: Install the control cable of bottom adjust-
ment lever to the front adjustment wheel of the A/C-
heater control.
(3) Hold the A/C-heater control in its installation
position.
Fig. 20 In-Car Temperature Sensor
1 - A/C-HEATER CONTROL
2 - IN-CAR TEMPERATURE SENSOR
Fig. 21 Air Distribution Control Cables
1 - AIR DISTRIBUTION CONTROL CABLES
2 - ADJUSTMENT LEVERS
3 - HVAC HOUSING
VACONTROLS-FRONT 24 - 21

OPERATION
The ISO-standard rear A/C clutch relay is an elec-
tromechanical switch that uses a low current input
from the rear A/C control module to control the high
current output to the rear A/C clutch. 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 con-
tact. This action allows high current to flow to the
A/C clutch field coil.
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
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 A/C clutch relay terminals are connected
to the vehicle electrical system through a receptacle
in the relay block located in the rear A/C evaporator
housing.
The rear A/C clutch relay cannot be repaired and,
if faulty or damaged, it must be replaced. Refer to
the appropriate wiring information for diagnosis 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 A/C clutch relay from the relay
block (Fig. 2).
Fig. 1 Rear A/C Clutch Relay
1 - STANDARD ISO RELAY
2 - TERMINAL PATTERN
VACONTROLS - REAR 24 - 25

INSTALLATION
(1) Position the rear A/C clutch relay into the
proper receptacle of the relay block located in the
rear A/C evaporator housing.
(2) Align the A/C clutch relay terminals with the
terminal cavities in the relay block receptacle and
push down firmly on the relay until the terminals
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 CONDENSER FAN RELAY
DESCRIPTION
The rear A/C condenser fan relay for the rear A/C
system is an International Standards Organization
(ISO)-type relay (Fig. 3). Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal functions and patterns.
The rear A/C condenser fan relay is an electrome-
chanical device that uses a low current input to con-
trol the high current output to the A/C condenser fan
for the rear heating-A/C system.
The rear A/C condenser fan relay is located in the
relay block in the rear A/C evaporator housing.
OPERATION
The ISO-standard rear A/C condenser fan relay is
an electromechanical switch that uses a low current
input from the rear A/C control module to control the
high current output to the rear A/C condenser cooling
fan. The movable, common feed relay contact is held
against the fixed, normally closed relay contact by
spring pressure. When the electromagnetic relay coil
Fig. 2 Rear A/C Clutch 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. 3 Rear A/C Condenser Fan Relay
1 - STANDARD ISO RELAY
2 - TERMINAL PATTERN
24 - 26 CONTROLS - REARVA

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 electric cooling fan motor.
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
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 A/C condenser fan relay terminals are
connected to the vehicle electrical system through a
receptacle in the relay block located in the rear A/C
evaporator housing.
The rear A/C condenser fan relay cannot be
repaired and, if faulty or damaged, it must be
replaced. Refer to the appropriate wiring information
for diagnosis 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 A/C condenser fan relay from
the relay block (Fig. 4).
VACONTROLS - REAR 24 - 27

input signals to control rear blower motor speed and
output air temperature, and to prevent freezing of
the rear evaporator core.
The rear A/C control module cannot be repaired
and, 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 wire harness connector from the
rear A/C control module (Fig. 6).
(4) Remove the two screws that secure the rear
A/C control module to the rear A/C evaporator hous-
ing and remove the control module.
VACONTROLS - REAR 24 - 29

rear A/C compressor operation when the rear dis-
charge line pressure approaches high levels, and also
reduces electrical surging from rear A/C clutch
engagement.
The rear A/C high pressure switch controls rear
A/C condenser cooling fan operation by monitoring
the rear discharge line pressure. When the rear dis-
charge pressure rises above approximately 1900 to
2200 kPa (280 to 320 psi) the rear A/C condenser
cooling fan will turn on. The rear condenser cooling
fan will turn off when the rear discharge pressure
drops to approximately 1600 kPa (235 psi).
The rear A/C high pressure switch contacts open
when the rear discharge line pressure rises above
approximately 3100 to 3375 kPa (450 to 490 psi). The
rear A/C high pressure switch contacts close when
the rear discharge line pressure drops to approxi-
mately 1860 to 2275 kPa (270 to 330 psi).
The rear A/C high pressure switch is factory-cali-
brated and cannot be adjusted or repaired and, if
faulty or damaged, it must be replaced. Refer to the
appropriate wiring information for complete HVAC
wiring diagrams.
REMOVAL
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.
(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) Recover the refrigerant from the rear refriger-
ant system (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY).
(4) Remove the cover from the rear A/C condenser
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C CON-
DENSER COVER - REMOVAL).
(5) Disconnect the wire harness connector from the
rear A/C high pressure switch (Fig. 8).
(6) Remove the rear A/C high pressure switch and
install a plug into, or tape over the opened rear dis-
charge line fitting.
INSTALLATION
NOTE: Replacement of the PTFE thread sealing
tape is required anytime the rear A/C high pressure
switch is removed from the rear discharge line. Fail-
ure to replace the sealing tape could result in a rear
refrigerant system leak.
(1) Remove the tape or plug from the rear dis-
charge line fitting.
(2) Install PTFE thread sealing tape onto the rear
A/C high pressure switch and install the switch onto
the rear discharge line. Tightened the A/C high pres-
sure switch to 10 N´m (88 in. lbs.).
(3) Connect the wiring harness connector to the
rear A/C high pressure switch.
(4) Reconnect the negative battery cable.
(5) Evacuate the rear refrigerant system (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING
- STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE).
(6) Charge the rear refrigerant system (Refer to 24
- HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE).
(7) Install the rear air filter (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION -
REAR/AIR FILTER - INSTALLATION).
(8) Install the cover onto the rear A/C condenser
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C CON-
DENSER COVER - INSTALLATION).
Fig. 8 Rear A/C High Pressure Switch
1 - REAR A/C CONDENSER
2 - WIRE HARNESS CONNECTOR
3 - REAR A/C HIGH PRESSURE SWITCH
4 - REAR DISCHARGE LINE FITTING
VACONTROLS - REAR 24 - 31

A / C LOW PRESSURE SWITCH
DESCRIPTION
The rear A/C low pressure switch provides a signal
to the rear A/C control module to regulate the rear
refrigerant system pressure and control rear A/C
evaporator temperature (Fig. 9). The rear A/C control
module will disengage the rear A/C clutch if the rear
refrigerant system suction line pressure falls below
30 kPa (4.4 psi).
The rear A/C low pressure switch is mounted on a
fitting located on the rear suction line near the left
side of the rear A/C evaporator housing.
The rear refrigerant system must be discharge
prior to removing the rear A/C low pressure switch.
OPERATION
The rear A/C low pressure switch is electrically
connected in series with the rear A/C high pressure
switch, between ground and the rear A/C control
module.
The rear A/C low pressure switch contact opens or
closes the path the ground, signaling the rear A/C
control module to turn the rear A/C clutch on and off.
This regulates the rear refrigerant system pressure
and controls rear A/C evaporator temperature. Con-
trolling the rear evaporator temperature prevents
condensate water on the evaporator fins from freez-
ing and obstructing rear A/C system air flow.
The rear A/C low pressure switch contacts are open
when the rear suction line pressure is approximately
152 kPa (22 psi) or lower. The rear A/C low pressure
switch contacts will close when the rear suction line
pressure rises to approximately 234 to 262 kPa (34 to
38 psi) or above. Lower ambient temperatures, belowapproximately -1É C (30É F), will also cause the rear
A/C low pressure switch contacts to open due to the
pressure/temperature relationship of the refrigerant
in the system.
The rear A/C low pressure switch is factory-cali-
brated and cannot be adjusted or repaired and, if
faulty or damaged, it must be replaced. Refer to the
appropriate wiring information for complete HVAC
wiring diagrams.
REMOVAL
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.
(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) Recover the refrigerant from the rear refriger-
ant system (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY).
(4) Remove the insulating tape from around the
area of the rear A/C low pressure switch (Fig. 10).
(5) Disconnect the wire harness connector from the
rear A/C low pressure switch.
(6) Remove the rear A/C low pressure switch and
install a plug into, or tape over the opened rear suc-
tion line fitting.
Fig. 9 Rear A/C Low Pressure Switch
1 - REAR PRESSURE SWITCH
2 - WIRE CONNECTOR
24 - 32 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