Basic fan operation

[g8dhe]

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...?

No that's correct for the scavenger Fan, its just a standard wound motor I presume.

I think the easiest way of checking the speeds on the radiator fans would be simple observation of the Fans whilst monitoring the temperature settings.The only other route requires knowledge of the programming of the ECU which is not a simple or easy job at all. Although perhaps just arranging to operate the relays manually might give us a good idea of what is likely to happen.

[Northern Bongolow]

ive fitted a pressure monitoring/warning system to my bongo and have just completed early tests,the results suggest that the thing that controls the top end pressure is the fans, this is simplified really as its the fans in relation to temps that does the biz in controlling pressure.
the stat opening/blending/controlling,does not have an impact on the pressures noted dirrectly(when the stat opens pressure does not drop) but indirectly this controls temps so adjusts the pressure.
the point at whiich the stat opens the pressure noted was 10 pounds.
the point where the fans cut in the pressure was 12-13 pounds.
fans drop out at 9-10 pounds.
as we know the cap lifts at 1'1 bar (approx 16 pounds).
this leaves a very narow margin for overhot/undercooling,before the lid blows off.
i put this here because as you can see the stat does the early temp control,but as the stat looses control the fans have a narrow window in which to do their stuff,if the switch is lazy/slow, or the coolant not up to scratch,or the flow restricted etc,things can get out of hand very quickly as some of the unfortunate have found.
hope this info helps.

[jaylee]

Am i right in thinking that the scavenger fan would cut in at the very last resort during this process...?

[widdowson2008]

I'm not electrical BUT from the circuit diagram:

Relays 1 and 3 are both activated simultaneously from ECU terminal 3Z, driving motors 1 & 2
Relay 2 is activated from ECU terminal 3S, driving motors 1 & 2

So

Could relay 2 be the one that the aircon fans are driven through?

Does this help identify stuff?

edit:
Sorry for jumping in Ady. Need to get the data from you for your pressure testing cos it needs to be logged. We WILL get this all tied together.
Talk to you on Sunday.

[daveblueozzie]

Am i right in thinking that the scavenger fan would cut in at the very last resort during this process...?

I am not sure if this is correct but isnt the scavenger fan controlled by a sensor that is located behind the handbrake and switches the fan on when the temp around the engine gets to a certain temperature.
or am i talking rubbish as usual.

[jaylee]

Am i right in thinking that the scavenger fan would cut in at the very last resort during this process...?

I am not sure if this is correct but isnt the scavenger fan controlled by a sensor that is located behind the handbrake and switches the fan on when the temp around the engine gets to a certain temperature.
or am i talking rubbish as usual.

Correct Dave! It hangs over the engine & triggers when the ambient engine bay temperature gets too hot.... Anyone know the exact/ish temp this happens??

[g8dhe]

+1 the Scavenger has its own sensor.

As to the relays and Air Con. etc the answer has to be possibly - unless we know how the ECU is programmed we don't know, it might be they have put a double wound motor in because it was available and one winding is Air Con. the other winding is radiator temperature cooling, but that seems like a very expensive option of a motor to me All we can say is that there is Black Box that has the sensors going in and relays operating Fans coming out what is inside the Box we don't know.... we can surmise all we like but there is no factual information to base the answer on...

[mikexgough]

Am i right in thinking that the scavenger fan would cut in at the very last resort during this process...?

I am not sure if this is correct but isnt the scavenger fan controlled by a sensor that is located behind the handbrake and switches the fan on when the temp around the engine gets to a certain temperature.
or am i talking rubbish as usual.

Correct Dave! It hangs over the engine & triggers when the ambient engine bay temperature gets too hot.... Anyone know the exact/ish temp this happens??

Manual quotes 60c as the trigger and as the sensor is relatively high up and triggered by hot air and not directly in coolant I would say that's the temp your looking for

[widdowson2008]

....Correct Dave! It hangs over the engine & triggers when the ambient engine bay temperature gets too hot.... Anyone know the exact/ish temp this happens??

Manual quotes 60c as the trigger and as the sensor is relatively high up and triggered by hot air and not directly in coolant I would say that's the temp your looking for

Yet another number slots into place . Good shot Mike.

[haydn callow]

Steve...I wouldn't let that diagram run tooooooo looooooong without a ex tank cap.

[jaylee]

Manual quotes 60c as the trigger and as the sensor is relatively high up and triggered by hot air and not directly in coolant I would say that's the temp your looking for

That pretty much makes sense to me with regards to the scav sensor test i did with a hair dryer the other day, i was getting near as damn it, a similar temp from the air shot it was getting... Cheers, all running lovely!

[widdowson2008]

Steve...I wouldn't let that diagram run tooooooo looooooong without a ex tank cap.

Wasn't ignoring your comment Haydn - just getting old and things take a long time to get round to these days.
However, cap duly fitted.

[haydn callow]

I feel more comfortable with it now.....nice one !! (1.1 Bar) ??

[gazza]

I'm not electrical BUT from the circuit diagram:

Relays 1 and 3 are both activated simultaneously from ECU terminal 3Z, driving motors 1 & 2
Relay 2 is activated from ECU terminal 3S, driving motors 1 & 2

So

Could relay 2 be the one that the aircon fans are driven through?

Does this help identify stuff?

edit:
Sorry for jumping in Ady. Need to get the data from you for your pressure testing cos it needs to be logged. We WILL get this all tied together.
Talk to you on Sunday.

Hi there, I seem to have a problem with my rad fans, they come on high speed when the sensor is disconnected, but the low speed fans don't cut in when the engine gets up to temp.
Is there any way of checking the low speed rad fan circuit? Does anyone know where these rad fan relays are fitted?

Thanks

Garry

[g8dhe]

The diagram below (click into it) shows the circuit and the next page shows the locations of the relays, the diagram is of the WL-T version choose the right page if it isn't what you have!