mirror RENAULT SCENIC 2010 J95 / 3.G Air Conditioning Workshop Manual

62A - 8
AIR CONDITIONING
Fault finding - Mode of operation62A
V4MR-372-J84-62A000$010.mif
Manual air conditioning
and
Climate controlAIR CONDITIONING
Fault finding - Mode of operation
General operation
The air conditioning system is composed of four sub-functions: heating, cold loop, passenger compartment
ventilation and user selection. Fault finding on the climate control is performed in two different ways using the
diagnostic tool.
The first procedure is by computer fault finding which makes it possible to communicate with just one computer
(select the computer concerned). The second procedure consists of performing fault finding by function which
allows communications to be established with all four computers of the AIR CONDITIONING function.
Description of the subsystems
Heating subsystem: this subsystem includes everything relating to the production of warm air in the vehicle and
management of the heated rear screen.
The main computers involved are the climate control computer (air mixing and blown air setpoint) and the UCH
(control and management of the passenger compartment heating resistors). The Protection and Switching Unit
controls the heated rear screen (and heated door mirror). The injection computer is only included in this subsystem
to supply the signals required for its management.
Cold loop subsystem: this subsystem includes everything involved in the vehicle's production of cold air.
The computers concerned are the climate control computer for air mixing, the injection computer to authorise
compressor engagement and the UPC to control the compressor and the engine fan units. On climate control
systems, the UCH merely transmits the request to engage the compressor from the climate control computer to the
injection computer.
On manual air conditioning systems, the UCH authorises or inhibits transmission of the request to engage the
compressor from the climate control computer to the injection computer depending on the status of the passenger
compartment blower (with manual air conditioning, the UCH receives and manages the passenger compartment
blower speed signal: compressor engagement is inhibited if the fan is not running).
User selection subsystem: this subsystem includes everything used to transmit the user's requests (pressing
buttons). The computers concerned are the climate control computer for climate control systems and the UCH. The
two other computers are not used for manual air conditioning.
Passenger compartment ventilation subsystem (climate control systems only): this subsystem includes
everything involved in ventilation, air mixing, air recirculation and air distribution. Therefore, only the climate control
computer is involved.
CLIM X84 1.1
Edition 2
MR-372-J84-62A000$040.mif

62A - 9
AIR CONDITIONING
Fault finding - Mode of operation62A
V4MR-372-J84-62A000$010.mif
Exchanges between the four air conditioning system computers
–air conditioning request 1 (compressor
engagement)
–switch on passenger compartment heating
resistors (RCH) request
–switch on heated rear screen request
(+ electric door mirrors)
–passenger compartment ventilation signal
Climate
control panelUCH
–passenger compartment heating resistors (RCH)
operation management
–exterior temperature signal
–engine coolant temperature signal
–switch on heated rear screen request
(+ electric door mirrors)
UCHUPC
(Power and Switching Unit)
–alternator charge signal
–number of passenger compartment heating
resistors authorised by alternator
–air conditioning request 2 (compressor
engagement)
–fast idle request for passenger compartment
heating resistors (RCH)
UCHInjection computer
–compressor engagement authorisation
–engine coolant temperature signal
–refrigerant fluid pressure signal
–number of passenger compartment heating
resistors authorised by injection
–compressor engagement request
–switch on engine cooling fan request
Injection computerUPC
(Power and Switching Unit)
–alternator charge signal
Manual air conditioning
and
Climate control
CLIM X84 1.1
Edition 2
MR-372-J84-62A000$040.mif

62A - 13
AIR CONDITIONING
Fault finding - Mode of operation62A
V4MR-372-J84-62A000$010.mif
Summary of components controlled or managed by the UCH
Summary of components controlled or managed by the Protection and Switching Unit
Passenger
compartment
heating
resistors (RCH)
relay No. 2 Passenger
compartment
heating
resistors (RCH)
relay No. 1 Passenger compartment
heating resistors (RCH)
relay No. 3 (Scénic only)Exterior
temperature
sensor
Vehicle
multiplex
network
Actuator control Sensor management
UCH
Air conditioning request
managementHeated rear screen
control
managementPassenger compart-
ment heating resistor
control management
Engine cooling
fan unitHeated rear
screen and
heated door
mirrorsClimate control
compressorAlternator:
"DF"
terminal
Actuator control Electrical availability management
UPC
"DF" terminal signal formatting
(alternator charge)
Key:
Wire connections =
Multiplex connections =
Manual air conditioning
and
Climate control
CLIM X84 1.1
Edition 2
MR-372-J84-62A000$040.mif

AIR CONDITIONING
Fault finding - Fault Finding Chart62A
62A-56V4 MR-372-J84-62A000$080.mif
Manual air conditioning
and
Climate control
ALP 10 Inefficient rear screen de-icing or demisting
NOTESOnly refer to this customer complaint after a full check with the diagnostic tool (fault
readings, especially those of the Protection and Switching Unit, and configuration
checks).
Special notes:
–Check that the inside of the glass is not greasy as this lowers the de-icing efficiency.
N.B.: for electric power drain reasons, de-icing can only be activated when the
engine is running.
Rear screen de-icing can be activated in two ways:
–Pressing the de-icing button (at the bottom of the control panel) switches on the
heated rear screen in manual mode (with timer) and heated door mirrors.
–Pressing the de-icing button at the top of the control panel activates the "See clear"
function: heated rear screen in automatic mode (no timer) heated door mirrors, air
conditioning and high speed windscreen ventilation all switched on.
Check that there are no water leaks into the passenger compartment
which would significantly increase the humidity levels and reduce the
effectiveness of demisting. Repair if necessary (see ALP 12).
Is the fault still present?
YES
Check for earth on the right-hand side terminal of the heated rear screen.
Repair if necessary.
Use the diagnostic tool to run command AC011 Heated
rear screen (Protection and Switching Unit command
mode menu).
Is the 12 V feed present on the left-hand connector
of the heated rear screen?
NO
NO
YESEnd of fault finding
procedure.
If the 12 V feed and earth both arrive
correctly at the heated rear screen
terminals but the screen still does not
operate correctly: unclip the plastic
rear screen pillars and check that the
de-icing lines are not broken. The
resistance of the lines should be
neither zero nor infinity (average
0.5 Ω). Repair if necessary.
AFTER REPAIRPerform a complete check using the diagnostic tool.
CLIM X84 1.1
Edition 2