Radiator fan
| Radiator fan |
The fan is controlled by the DICE system through the following input signal:
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Coolant temperature (bus from PSG 16)
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A/C pressure
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Car speed (bus from MIU)
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Outside temperature (bus from SID)
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The radiator fan is activated when the coolant temperature is equal to or exceeds the programmed values as well as when the AC compressor is activated and
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the outside temperature exceeds 22°C (72°F)
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vehicle speed is below 38 km/h and the AC pressure exceeds 9 bar.
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DICE receives the information regarding coolant temperature and AC system pressure on the bus.
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Warning
| 2-speed radiator fan |
The cars are equipped with an electric radiator fan positioned behind the radiator. The radiator fan has two speeds, low speed/high speed.
DICE controls the radiator fan through the following input signals:
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Coolant temperature (bus from PSG 16)
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A/C pressure
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Car speed (bus from MIU)
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Outside temperature (bus from SID)
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The radiator fan will start during the following conditions:
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The fan will run at low speed when the coolant temperature is equal to or exceeds 99°C (210°F). If the temperature increases to 108°C (226°F), the fan will run at high speed.
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When the A/C compressor is activated, the fans start running at low speed in one of the following cases:
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the outside temperature exceeds 22°C (72°F)
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The car speed is below 38 km/h and the AC system pressure is above 9 bar.
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When the A/C compressor is activated, the fans start running at high speed if A/C pressure exceeds 18 bar.
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The DICE receives information on the coolant temperature via the bus. The pressure in the A/C system is obtained via its own pressure sensor.
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| Function, 1-speed radiator fan |
The fan operation is dependent on the coolant temperature, AC pressure, car speed and the outside temperature.
DICE controls the radiator fan via a relay (155).
Regardless of the position of the ignition, power is supplied from fuse 15 to the relay (155).
DICE uses the value of the coolant temperature that fulfils the conditions for start. The relay (155) is then grounded via pin 35 on the control module.
Power is supplied to the radiator fan which then starts.
| Function, 2-speed radiator fan |
The radiator fan may, depending on coolant temperature, AC pressure, car speed and outside temperature, be run at two speeds:
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Low speed
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High speed
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The radiator fan is controlled by the DICE system via two relays, (155) and (81).
Regardless of the ignition position, power is supplied via fuse 15 to relay (155) and relay (81) for low speed operation.
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Low speed, only relay (155) operated
DICE uses the values which meet the conditions for low speed. The relay (155) is then grounded via pin 35 of the control unit. Power is supplied to the radiator fan which starts running at low speed since the current is reduced by a serial resistor (367). |
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High speed, all relays operated
DICE uses the values which meet the conditions for high speed. The relay (81) is then grounded via pin 53 on the control unit which means that the radiator fan is grounded directly. Relay (155) still operates. The radiator fan now runs at high speed. |
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| Operation with ignition ON |
When the ignition is in the ON position, DICE uses the following information on the bus:
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Coolant temperature (bus from PSG 16)
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A/C pressure
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Car speed (bus from MIU)
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Outside temperature (bus from SID)
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A/C system status (active/inactive)
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The information is used in DICE and controls if the radiator fan is to start or stop.
In order to maintain constant idle rpm value, DICE sends information of estimated power consumption on the bus to the engine control system. The in formation is sent 0.1 seconds before DICE starts or stops the radiator fan.
When the conditions for high speed are fulfilled, low speed should be active for 2 seconds before high speed is activated. If high speed is active and the conditions for stopping both low speed and high speed are fulfilled, high speed is stopped immediately and low speed is stopped after 2 seconds.
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High speed cannot be activated until 15 seconds after the ignition has been turned on. |
Diagnosis
If the coolant temperature sensor is outside the value range or if the coolant temperature information is absent, DICE will start low speed after 5 seconds.Fault code generated in PSG 16, see Group 2 - Engine management system PSG 16 - Fault diagnosis, fault codes
for further information.
DICE receives information about coolant temperature from PSG 16.
The radiator fan is activated as follows:
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Low speed
Activated when coolant temperature is above 99°C (210°F) and is deactivated 50 seconds after the temperature has dropped below 96°C (205°F). |
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High speed
Activated when the coolant temperature exceeds 108°C (226°F) and is deactivated when the temperature has dropped below 105°C (221°F). |
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When A/C is requested, some conditions must be fulfilled in the DICE as well as PSG 16 for the A/C compressor clutch to operate. For further information with regards to A/C and its control, see Group 8, Heating and ventilation, A/C, Technical description, ”A/C”
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For further information on the coolant temperature sensor, see Coolant temperature sensor, engine management system .
When the A/C clutch operates, the radiator fan is activated according to the following conditions:
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Low speed
Activated when the outside temperature exceeds 22°C (72°F) and is deactivated when the outside temperature has dropped below 20°C (68°). |
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Low speed
Vehicle speed is below 38 km/h while A/C pressure exceeds 9 bar. Low speed running stops when vehicle speed exceeds 40 km/h or A/C pressure drops below 7 bar. |
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| 3. |
High speed
A/C pressure exceeds 18 bar. High speed running stops when A/C pressure is below 14 bar. |
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To understand the operation of the radiator fan, it is important to note that it can be activated differently at the same value (within certain preset limits), depending on if the value is increasing or decreasing.
For example, if the coolant temperature is 98°C (208°F) low speed is activated if the temperature has been 99°C (210°F) or higher and has now dropped to 98°C (208°F). However, if low speed has not been activated and the coolant temperature is 98°C (208°F), then low speed is not activated.
| Function with ignition OFF |
DICE receives information on coolant temperature from PSG 16 when the ignition is turned OFF, after a further 30 seconds and 1 minute after the ignition has been turned OFF.
In order to receive this information, DICE needs to keep the MIU active for one minute. From this information, DICE can activate low speed operation for a maximum of 3.5 minutes.
Note that only low speed operation is activated with the ignition OFF.
Radiator fan does not run when ignition is turned from ON to OFF
30 seconds after ignition OFF:| • |
The radiator fan starts and operates for 3 minutes if the coolant temperature exceeds or is equal to 107°C (225°F). The radiator fan stops operating after 3 minutes.
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The radiator fan starts and operates for 30 seconds if the coolant temperature is between 103°C (217°F) and 107°C (225°F).
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1 minute after the ignition is turned to the OFF position (only applicable if coolant temperature was between 103°C (217°F) and 107°C (225°F) 30 seconds after ignition OFF):
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The radiator fan keeps operating for 3 minutes if the coolant temperature exceeds or is equal to 107°C (225°F).
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The radiator fan stops operating if the coolant temperature is below 107°C (225°F).
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The radiator fan operates at low speed when ignition is turned from ON to OFF
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The radiator fan keeps operating for 30 seconds if the coolant temperature exceeds or is equal to 103°C (217°F).
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The radiator fan stops operating if the coolant temperature is below 103°C (217°F).
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30 seconds after ignition OFF:
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If the radiator fan did not stop at ignition OFF, then the fan continues to operate for 3 minutes if the coolant temperature exceeds or is equal to 107°C (225°F). The fan stops after 3 minutes. If the coolant temperature is below 107°C (225°F), the fan stops.
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If the radiator fan stopped at ignition OFF, the fan will start and operate for 3 minutes if the coolant temperature exceeds or is equal to 107°C (225°F). The fan stops after 3 minutes. If the coolant temperature is between 103°C (217°F) and 107°C (225°F), the fan will start to operate and runs for 30 seconds. The radiator fan stops if the coolant temperature is below 103°C (217°F).
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1 minute after the ignition is turned to the OFF position (only applicable if coolant temperature was between 103°C (217°F) and 107°C (225°F) 30 seconds after ignition OFF):
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The radiator fan keeps operating for 3 minutes if the coolant temperature exceeds or is equal to 107°C (225°F).
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The radiator fan stops operating if the coolant temperature is below 107°C (225°F).
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The radiator fan runs at high speed when ignition is turned from ON to OFF
Immediately after the ignition is turned OFF, the radiator fan will start and run at low speed for 2 seconds. After these 2 seconds, the same logic applies as when the fan operates at low speed when ignition is turned from ON to OFF:This project is supported by memberships and donations. If you use this site, please consider Joining SCNA and/or making a donation.
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