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 EDC 15)
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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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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.
The radiator fan is controlled by DICE through the following input signals:
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Coolant temperature (bus from EDC 15)
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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 under the following conditions:
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When the coolant temperature is greater or equal to 99°C (210°F), the fan starts at low speed. If the temperature rises to 108°C (226°F) high speed is engaged.
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| 2. |
When the A/C compressor is activated, the fans start running at low speed in one of the following cases:
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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.
The radiator fan is controlled by DICE 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 EDC 15)
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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 management 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.Diagnostic trouble code is generated in EDC 15, see group 2, Engine management system EDC 15, Fault diagnosis, fault codes
for further information.
DICE receives coolant temperature information from EDC 15.
The radiator fan is activated as follows:
| 1. |
Low speed
Activated when the coolant temperature exceeds 99°C (210°F) and switched off 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 switched off when the temperature drops 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 EDC 15 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 group 2, Engine management system EDC 15, Technical description
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When the AC 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 switched off when the outside temperature drops below 20°C (68°F). |
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| 2. |
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.
If coolant temperature is 98°C, (208°F) for instance, low speed will be activated if the temperature was previously 99°C (210°F) or above and has now fallen to 98°C (208°F). However, if low speed had not been activated and the coolant temperature is 98°C (208°F), low speed will not be activated.
| Function with ignition OFF |
DICE receives coolant temperature information from EDC 15 at ignition OFF after 30 seconds as well as after 1 minute when the ignition is in the OFF position.
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 runs for 3 minutes if the coolant temperature is 107°C (225°F) or above. After 3 minutes the fan stops.
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The radiator fan starts and runs 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 ignition OFF (only 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 continues to run for 3 minutes if the coolant temperature is 107°C (225°F) or above.
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The radiator fan stops 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 continues to run for 30 seconds if the coolant temperature is 103°C (217°F) or above.
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The radiator fan stops 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 when the ignition was turned OFF, it will continue to run for 3 minutes if the coolant temperature is 107°C (225°F) or above. After 3 minutes the fan will stop. If the coolant temperature is below 107°C (225°F) the fan will stop.
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If the radiator fan stopped when the ignition was turned OFF, it will start and run for 3 minutes if the coolant temperature is 107°C (225°F) or above. After 3 minutes the fan will stop. If the coolant temperature is between 103°C (217°F) and 107°C (225°F), the fan will start and run for 30 seconds. If the coolant temperature is below 103°C (217°F) the fan will stop.
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1 minute after ignition OFF (only 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 continues to run for 3 minutes if the coolant temperature is 107°C (225°F) or above.
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The radiator fan stops 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 ignition is turned OFF, the radiator fan will start and run at low speed for 2 seconds. After these 2 seconds, the same logistics apply 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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