Volvo 850. Instruction - page 59
temperature control dial, and engine coolant temperature.
At low outside temperatures, the ECC control module selects
floor/defrost setting, with a slight amount of bi-level air if
sunshine is present. If outside temperature is between 50-66
F (10-
19
C), a varying degree of bi-level air is selected. At temperatures
greater than 68
F (20
C), all air is directed to instrument panel
vents.
The ventilation air distribution setting is selected if
driver’s side control panel is set for maximum cooling. The
floor/defrost setting is selected if maximum heating is selected.
The defrost air distribution setting is selected if engine is
cold and outside and interior temperatures are also low. This changes
to varying degrees of floor/defrost air distribution as engine coolant
temperature increases. The transition from defroster to
floor/defroster setting takes place more quickly in sunshine.
AIR TEMPERATURE SENSORS & SOLAR SENSOR
Two interior temperature sensors and 2 duct temperature
sensors are required for individual temperature control of driver’s
and passenger’s sides. Each interior temperature sensor incorporates a
fan which draws air through sensor.
The resistance of the air temperature sensors decreases as
temperature increases. The solar sensor, combined with the theft alarm
diode, is a photodiode which generates a current when exposed to solar
radiation.
DAMPER MOTORS
The temperature control damper motors, recirculation damper
motor, floor/defroster damper motor, and ventilation damper motor are
all identical, but their control range varies according to the damper
being controlled.
The damper motors have a position sensor to enable the ECC
control module to determine damper position, learn the damper limit
positions, and to detect any fault in damper motor. The ventilation
damper is operated by damper motor through 2 gear segments; one fitted
to damper motor shaft and the other on ventilation damper shaft.
FAN CONTROL
Heater (blower motor) fan speed is variably controlled by ECC
output (power) stage in response to signals from ECC control module.
The ECC control module digital control signals vary in length
according to required fan speed.
The ECC output stage has an electronic unit which receives
the digital control signals and converts them to voltage. If there is
no control signal or the fan is disabled, the ECC output stage sends a
diagnostic signal to inform the ECC control module of the fault.
If fan speed control lever is set to AUT (automatic) mode,
fan speed is influenced by the position of driver’s side temperature
control dial, driver’s side interior temperature sensor, vehicle
speed, and engine coolant temperature.
The highest fan speed is selected if driver’s side
temperature control dial is set to maximum or minimum cooling or
heating. The greater the difference between the desired and actual
temperatures, as sensed by the driver’s side temperature sensor, the
higher the fan speed.
As vehicle speed increases, the fan speed will be reduced to
maintain a constant airflow throughout the passenger compartment. When
heating the passenger compartment after starting a cold engine, the
fan speed is gradually increased as engine coolant temperature rises.
RECIRCULATED AIR MODE
The ECC control module selects recirculated air mode only for
a combination of cooling and high outside temperature, provided that:
* There is a considerable difference between the desired and
actual temperature on driver’s side. The quantity of
recirculated air will vary between 70-100 percent, depending
on difference in temperature.
* A high fan speed is manually selected. In this case, the
recirculation damper will be set to a mid-position (50
percent of the air will be recirculated).
Recirculation Motor
This motor operates the recirculation damper by means of a
mechanical linkage in response to signals from ECC control module.
Recirculation Switch
The off position of REC (recirculation) switch corresponds to
automatic operation, the ECC control module determines whether
recirculation is required.
Air Distribution Switch
With air distribution switch in defroster position,
recirculated air mode always cuts out, as humidity in passenger
compartment will normally be higher than that of outside air.
Recirculation Damper
In AUT (automatic) mode, recirculation damper movement is
limited to fractions of a second. It takes about half a minute from
full recirculation to take effect if outside temperature is high.
TEMPERATURE CONTROL
Individual temperature control is provided by the driver’s
and passenger’s side temperature control damper motors in response to
signals from ECC control module.
The ECC control module computes temperature control damper
motors based on inputs from temperature dial settings, duct
temperature sensors, interior temperature sensors, solar sensor,
engine coolant temperature sensor, and outside (ambient) temperature
sensor.
The air temperature is monitored downstream of temperature
control dampers by the duct temperature sensors. The difference
between the desired and actual interior temperature, as monitored by
interior temperature sensors, has a direct effect on temperature
control damper positions.
In direct sunlight, the temperature control dampers are
positioned to provide a lower temperature, as determined by solar
sensor input. If the engine is cold and outside temperature is low,
the temperature control dampers are set for more heat to reach the
desired temperature faster.
TROUBLE SHOOTING
SELF-DIAGNOSTICS
The Electronic Climate Control (ECC) control module can
detect faults in the system and store Diagnostic Trouble Codes (DTCs).
If a fault is present, system informs driver by flashing AC OFF and
REC switch LEDs for 20 seconds.
A fault warning is given when a fault is discovered or
present each time ignition is turned on or engine started. DTCs will
remain stored until cleared by an input code.
NOTE: Test Unit (981 3190) and Adapter (981 3194) are required for
DTC diagnosis. The Volvo Diagnostic Key (998 8670) may be
used to perform self-diagnostics. Follow tool manufacturer’s
instructions.
There are 3 different test modes/settings which can be
selected for reading off DTCs. TEST MODE 1 may be used for reading off
DTCs detected by control unit (up to 47 codes can be stored). TEST
MODE 2 checks signals from speedometer and solar sensor.
TEST MODE 4 is used to check electrical circuits in A/C
system, reset information on damper motor limit positions and change
data transmission speed from ECC control module to on-board diagnostic
unit.
NOTE: Ignition must be turned off before switching from one test
mode to another.
ENTERING SELF-DIAGNOSTICS
1) Connect selector cable from diagnostic unit "A" to
terminal No. 1 of diagnostic unit "B", located behind right headlight.
See Fig. 2.
2) Turn ignition on. LED on diagnostic unit "A" should start
flashing. Each DTC (3-digits) consists of a series of flashes with a
short break between each series. DTCs are displayed in ascending
order. See AUTOMATIC A/C-HEATER SYSTEM DIAGNOSTIC TROUBLE CODES table.
Fig. 2: Identifying Diagnostic Units
Courtesy of Volvo Cars of North America.
AUTOMATIC A/C-HEATER SYSTEM DIAGNOSTIC TROUBLE CODES
Code # Condition/Affected Circuit
1-1-1 ..................... No Fault Found By Diagnostic System
1-2-1 .......... Outside Temp. Sensor Circuit Shorted To Ground
1-2-2 .................................... Outside Temp. Sensor
Circuit Open Or Shorted To Power
1-2-3 .... Driver’s Side Temp. Sensor Circuit Shorted To Ground
1-2-4 .............................. Driver’s Side Temp. Sensor
Circuit Open Or Shorted To Power
1-2-5 ....... Pass. Side Temp. Sensor Circuit Shorted To Ground
1-2-6 ................................. Pass. Side Temp. Sensor
Circuit Open Or Shorted To Power
1-3-1 ....... Driver’s Side Duct Temp. Sensor Shorted To Ground
1-3-2 ......................... Driver’s Side Duct Temp. Sensor
Circuit Open Or Shorted To Power
1-3-3 .......... Pass. Side Duct Temp. Sensor Shorted To Ground
1-3-4 ............................ Pass. Side Duct Temp. Sensor
Circuit Open Or Shorted To Power
1-3-5 ........................ No Engine Temp. Frequency Signal
1-4-1 ........ Driver’s Side Temp. Switch Faulty Control Signal
1-4-3 ........... Pass. Side Temp. Switch Faulty Control Signal
1-4-5 ........... Air Distribution Switch Faulty Control Signal
1-5-1 ..... Fan Speed Sensor Control Signal Missing Or Too High
1-5-2 ....... Fan Speed Sensor Control Signal Shorted to Ground
2-1-1 .............. Driver’s Side Damper Motor Position Sensor
Circuit Open Or Shorted To Power
2-1-2 .............. Driver’s Side Damper Motor Position Sensor
Shorted To Ground
2-2-1 ................. Pass. Side Damper Motor Position Sensor
Circuit Open Or Shorted To Power
2-2-2 ................. Pass. Side Damper Motor Position Sensor
Shorted To Ground
2-3-1 ................ Ventilation Damper Motor Position Sensor
Circuit Open Or Shorted To Power
2-3-2 ................ Ventilation Damper Motor Position Sensor
Shorted To Ground
2-3-3 .............. Floor/Defrost Damper Motor Position Sensor
Circuit Open Or Short To Power
2-3-4 .............. Floor/Defrost Damper Motor Position Sensor
Shorted To Ground
2-3-5 .............. Recirculation Damper Motor Position Sensor
Circuit Open Or Short To Power
2-3-6 ..................... Recirculation Damper Motor Position
Sensor Shorted To Ground
3-1-1 ... Driver’s Side Damper Motor Shorted To Ground Or Power
3-1-2 ...... Pass. Side Damper Motor Shorted To Ground Or Power
3-1-3 ..... Ventilation Damper Motor Shorted To Ground Or Power
3-1-4 ... Floor/Defrost Damper Motor Shorted To Ground Or Power
3-1-5 ... Recirculation Damper Motor Shorted To Ground Or Power
3-2-1 .............. Driver’s Side Damper Motor Active Too Long
3-2-2 ................. Pass. Side Damper Motor Active Too Long
3-2-3 ................ Ventilation Damper Motor Active Too Long
3-2-4 .............. Floor/Defrost Damper Motor Active Too Long
3-2-5 .............. Recirculation Damper Motor Active Too Long
4-1-1 ......... Pass. Compartment Fan Overcurrent Or Seized Fan
4-1-2 .............................. Driver’s Side Temp. Sensor
Intake Fan Shorted To Ground
4-1-3 .............................. Driver’s Side Temp. Sensor
Intake Fan, No Control Voltage
4-1-4 ............ Driver’s Side Temp. Sensor Intake Fan Seized
4-1-5 .... Pass. Side Temp. Sensor Intake Fan Shorted To Ground
4-1-6 .. Pass. Side Temp. Sensor Intake Fan, No Control Voltage
4-1-7 ............... Pass. Side Temp. Sensor Intake Fan Seized
