Basic fan operation

[widdowson2008]

This query seems to have come up a couple of times recently, so I did the following. I think it's right, but if there are any errors, please let me know.

Basic fan operation

The main radiator fans are controlled by the ECU.
The ECU receives a signal from an engine temperature sensor located on the driver side of the engine.
When this temperature reaches 96°C, the fans are switched on by the ECU at low speed.
When this temperature reaches 104°C, the fans are switched on by the ECU at high speed.
(see attached pic)

[binky]

That is rather fine.

[g8dhe]

You can check that the Fans, the relays that operate them and fuses are OK by using the Air Con. I believe as well, as that turns the fans, on not sure what speed however.

[mikexgough]

Nice work Steve, just one thing.....I think the high temperature 108c according to the manual

[widdowson2008]

Nice work Steve, just one thing.....I think the high temperature 108c according to the manual

Oooops
Back to the drawing board

Is this right Mike?

[jaylee]

Hi Steve, with the reference to fan speed... Is there an actual change in speed due to a resistor pack like the heater fan, but ECU controlled. Or just a case of near side rad fan kicks in at 96 & off side joins in at 108... Both on with AC anyway?? Hope this question makes sense!?

[widdowson2008]

Hi Steve, with the reference to fan speed... Is there an actual change in speed due to a resistor pack like the heater fan, but ECU controlled. Or just a case of near side rad fan kicks in at 96 & off side joins in at 108... Both on with AC anyway?? Hope this question makes sense!?

Hi Jamie
Geoff will probably confirm this (hopefully) but from the circuit diagrams it is my understanding that the fans work simultaneously - ie both on at low speed (96) and then both on at high speed (108). Diagram IS a little misleading I have to admit. The 2 fans at high speed ????? Couldn't get the software to speed up a single fan. May go back and try again
Not sure about the resistor pack but I'm sure Geoff can clear up this query. ................GEOFFFFFF

[g8dhe]

The fans have TWO sets of commutators and hence TWO sets of brushes, so a total of 4 connections rather than the normally expected 2 connections for a motor;

These are switched separately and hence there is more than 1 speed available, I say that because the lowest speed setting is controlled by relay B6-01, however there are two more relays B6-02 and B6-03 which are controlled separately, so its quite possible that there are more than 2 speeds available - I only have a V6 not a diesel which is different so not in a position to actually experiment to find out just how many speed settings there are, but at least two and possibly 3 and remotely possible is 4, it will depend just how the windings are connected inside the motor.

[bigdaddycain]

Nice work with the illustrations Steve

[widdowson2008]

Thanks ste. However, it's only good enough if it's correct, and from what Geoff is saying there appears to be a raft of possibile combinations. Only one way to get to the truth really, and that's to take one apart . Any takers?

Another thing that has just occured to me is that the pic shows when the fans are switched ON. They do not switch OFF at these same temperatures. For example, the low speed switches ON at 96 but switches off at 92 (I think). So the pic is far from the whole FAN sequence. Just gets more and more complex.

[bigdaddycain]

Only one way to get to the truth really, and that's to take one apart . Any takers?

Sorry Steve... Did you say summat?

[widdowson2008]

Perhaps Geoff or some other leccy wizzard can sort it out.

[bigdaddycain]

Thanks ste. However, it's only good enough if it's correct, and from what Geoff is saying there appears to be a raft of possibile combinations. Only one way to get to the truth really, and that's to take one apart . Any takers?

Another thing that has just occured to me is that the pic shows when the fans are switched ON. They do not switch OFF at these same temperatures. For example, the low speed switches ON at 96 but switches off at 92 (I think). So the pic is far from the whole FAN sequence. Just gets more and more complex.

Aye... You've taken something on there alright!

[widdowson2008]

Aye... You've taken something on their alright!

Can be done.......IF I know the full story. Becomes a pain if I need to backtrack and alter stuff. I only understand the basics of this software.

[jaylee]

The fans have TWO sets of commutators and hence TWO sets of brushes, so a total of 4 connections rather than the normally expected 2 connections for a motor;

These are switched separately and hence there is more than 1 speed available, I say that because the lowest speed setting is controlled by relay B6-01, however there are two more relays B6-02 and B6-03 which are controlled separately, so its quite possible that there are more than 2 speeds available - I only have a V6 not a diesel which is different so not in a position to actually experiment to find out just how many speed settings there are, but at least two and possibly 3 and remotely possible is 4, it will depend just how the windings are connected inside the motor.

Looking at the diagram Geoff, relay B6-06 is set up for a single speed for the scavenger fan?? Or do i interpret that wrong...?