Auxillary Fan Operation

[shimmy]

Can anybody who really knows, try to explain to me how, when, and why he Auxillary electric fan operates in he S54 lump in our cars.

I'm keen to know what criteria turns it on and off.

(I'm nt talking about the mechanics clutch fan on the engine side of the rad but the electric fan you see from the front grill)

[mattCSLnut]

Isn't that the A/C electric cooling assist fan for when one's stuck in slow moving traffic with the A/C On
It usually comes on when the natural air flow to the A/C rad (which is in front of the main engine cooling rad ) is reduced, most noticeably is slow city driving on a hot day) as the temperature of the A/C gasses increases requiring additional cooling.
IIRC none A/C Cecils don't have this AUX electric fan.

[shimmy]

Originally Posted by mattCSLnut

Isn't that the A/C electric cooling assist fan for when one's stuck in slow moving traffic with the A/C On
It usually comes on when the natural air flow to the A/C rad (which is in front of the main engine cooling rad ) is reduced, most noticeably is slow city driving on a hot day) as the temperature of the A/C gasses increases requiring additional cooling.
IIRC none A/C Cecils don't have this AUX electric fan.

That's the one, just need to know exactly how it works and why it is needed

[alexk]

shimmy, I could be wrong but I think the electric fan is also installed on the non-AC cars.

The fan is used to provide additional cooling to the engine. It's not used just for the AC.

Here are the maps that show how the fan is operated.

Temperature (°C)|Operation/speed (%)
|49°C|0%
|50°C|30%
|70°C|40%
|80°C|65%
|85°C|83%
|90°C|100%

The second map, that changes the voltage supply depending on the speed.
Above 140km/h it's deactivated.

speed (km/h)|Voltage (index)
|0 km/h|1
|50 km/h|1
|100 km/h|1
|120 km/h|0.5
|140 km/h|0
|200 km/h|0

[shimmy]

Alex.........brill.


So above 140kph or 87.5mph the Aux fan stops nd ultimately blocks air into the front of the car.


Any idea why they would do this?

How could you have a switch to override it to let it run above 140kph?

[O'Neill]

Originally Posted by shimmy

Alex.........brill.


So above 140kph or 87.5mph the Aux fan stops nd ultimately blocks air into the front of the car.


Any idea why they would do this?

How could you have a switch to override it to let it run above 140kph?

At that speed the air turning the fan would turn fan faster than the motor.

[O'Neill]

Might not though due to pressure.

[shimmy]

Originally Posted by O'Neill

At that speed the air turning the fan would turn fan faster than the motor.

I need to put a camera on it and see if it is held stationary by the motor when not powered.


.

[alexk]

Originally Posted by shimmy

How could you have a switch to override it to let it run above 140kph?

This is the map in the ECU.
Changing the map would change the behavior.
But I think O'Neil is right about the speed of air.

[shimmy]

Originally Posted by alexk

shimmy, I could be wrong but I think the electric fan is also installed on the non-AC cars.

The fan is used to provide additional cooling to the engine. It's not used just for the AC.

Here are the maps that show how the fan is operated.

Temperature (°C)|Operation/speed (%)
|49°C|0%
|50°C|30%
|70°C|40%
|80°C|65%
|85°C|83%
|90°C|100%

The second map, that changes the voltage supply depending on the speed.
Above 140km/h it's deactivated.

speed (km/h)|Voltage (index)
|0 km/h|1
|50 km/h|1
|100 km/h|1
|120 km/h|0.5
|140 km/h|0
|200 km/h|0

What about viscous fan guys?