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Scavenger Fan Override?

Posted: Wed Aug 12, 2015 12:17 pm
by Mark Elvin
Has anybody fitted an override switch to the scavenger fan om their Bongo?

Re: Scavenger Fan Override?

Posted: Wed Aug 12, 2015 12:26 pm
by Simon Jones

Re: Scavenger Fan Override?

Posted: Wed Aug 12, 2015 1:35 pm
by lancyman
For what reason? For when it's getting hot?
If so, you can put aircon on and open the windows.
I was advised of this by Northern bongolow (Ady)
The other week and it worked a treat when I was stuck in
Traffic. Dropped about 5 degrees in ten minutes.

Re: Scavenger Fan Override?

Posted: Wed Aug 12, 2015 2:52 pm
by Gasy
The scavenger fan will drop it quicker than that ^^^

Re: Scavenger Fan Override?

Posted: Wed Aug 12, 2015 11:52 pm
by sotal
Is the scavenger fan the one you can see when you lift the passenger seat? Electric fan at the front of the engine bay?

Am I right that if I start the engine and switch the A/C on it should start straight away?

Only asking as I tried that earlier and it didn't come on (Bongo wasn't up to temperature). Is the scavenger fan something you can hear when it starts - not noticed it all.

Re: Scavenger Fan Override?

Posted: Thu Aug 13, 2015 10:18 am
by g8dhe
Yes that is the fan, No it doesn't start with the A/C, the air con starts the radiator fans behind the radiator to cool the A/C radiaitor that sits in front of the engine cooling radiator, which is why turning on the A/C helps cool the engine down when its hot!.

Re: Scavenger Fan Override?

Posted: Thu Aug 13, 2015 8:47 pm
by sotal
So when does the scavenger fan start?

I found the temp sender by the handbrake - is it worth shorting that just to check that it does work?

As I say I have never noticed any noise of the fan (would you notice?)

Re: Scavenger Fan Override?

Posted: Thu Aug 13, 2015 10:03 pm
by g8dhe
Its starts when the temperature sensor by the handbrake tells it to via the ECU, it measures the temperature of the engine bay itself not the engine as such! 60°C according to here http://www.igmaynard.co.uk/bongo/forum/ ... 26#p497026

Re: Scavenger Fan Override?

Posted: Fri Aug 14, 2015 11:04 am
by windywatson
I fitted a switch across the sensor in the engine tunnel by hand brake that effectively switches a short across the sensor & kicks the fan in. However this does make the charge light flash on the dash as it registers this as a fault. However as I only us it occasionally I don't mind the flashing light for the short time its on.
I suspect that it really ought to have at least a resistor of some type fitted so that it is not being seen as a fault. As the actual sensor drops in value as it heats up and doesn't actually go completely to zero ohms. But it does what I want it to.

Re: Scavenger Fan Override?

Posted: Fri Aug 14, 2015 11:17 am
by g8dhe
Try a 270Ω resistor thats the resistance of the sensor at 80°C

Re: Scavenger Fan Override?

Posted: Fri Aug 14, 2015 2:51 pm
by Northern Bongolow
windywatson wrote:I fitted a switch across the sensor in the engine tunnel by hand brake that effectively switches a short across the sensor & kicks the fan in. However this does make the charge light flash on the dash as it registers this as a fault. However as I only us it occasionally I don't mind the flashing light for the short time its on.
I suspect that it really ought to have at least a resistor of some type fitted so that it is not being seen as a fault. As the actual sensor drops in value as it heats up and doesn't actually go completely to zero ohms. But it does what I want it to.
spot on mate, thats the reason i dont do a simple shorting out or switch in the scav system, the ecu may not like it. turn the aircon on is much easier and safer.
a well maintained system shouldnt really need any help at all, but i like to keep things cool in extreme conditions rather than trying to cool something down that is already hot.

Re: Scavenger Fan Override?

Posted: Fri Aug 14, 2015 5:15 pm
by petebee
I by passed my sensor because my sound killer sheet cuts it off from the engine,with no side effects.When I tow my caravan I switch it permanently only problem is the led on the switch wont light because there is only a 5 volt feed.

Re: Scavenger Fan Override?

Posted: Sat Aug 15, 2015 12:07 pm
by Gasy
I've bypassed / switched mine
A couple of years back
No probs yet
Will be fitting a resistors soon ish
Will be using switch quite abit today as we travelling home from devon at Exeter services at mo
Fingers crossed for a good safe journey

Re: Scavenger Fan Override?

Posted: Sun Aug 16, 2015 10:47 pm
by the1andonly
Yes: viewtopic.php?f=3&t=67626&hilit=scavenger+switch
My orig post

now used 330ohm in parallel with sensor since oct last year
after ignition is off fan stays on for a few minutes.
just returned from holiday 5 hr run (towing 1000kg) and then ponsing about waiting and reversing
engine still ok 92 at rear of head but engine compartment up in seventies and gearbox 71.
gearbox rarely runs above 60C (sensor bolted on outside of gearbox) only on long slogs uphill typically in 50's
switch on override
every bodies happy even deals with head soak

Re: Scavenger Fan Override?

Posted: Wed Aug 19, 2015 5:02 pm
by Fassi
Modified mine today so I've the option. Used a switch and 400 ohm resistor in parallel as it was the closest I had. With the head temp <=83 the switch would just operate on and off as you used it and only if the ignition was on. No fan with ignition off. At 84 degrees the fan was able to be turned on with ignition off and would run for 5 minutes before switching itself off. Quite happy with this, cheers =D>