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Discussion Starter #1
On the R53, how is the fan switched from high speed to low speed?

There is a relay for each I realise, but does the low speed relay switch off as the high speed switches on?

Reason I ask - my resistor is fucked - has been for quite a while now and I really need to sort it out.

Was considering getting a Kenlowe fan with 2 speeds built into the motor winding, which means I would be able to move the fan to the outside of the radiator as I have wanted to do for a project I'm working on, plus it would do away with having a stupid resistor to drop the power across the fan winding.

Cheers
Karl
 

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Just did this mod myself. I doubt there are many R53's around with a working low speed. The stock ones don't last long at all.
 

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I bought a strip of aluminium to mount mine as shown above, with thermal paste in between.
I cut out the old resistor, disconnected the wires to the fan terminals, joined 2 lengths of the thickest (high current) electrical wire up to the resistor, polarity doesn't matter with resistors. You can pretty much mount it anywhere that acts as a heat sink.

Its great not to hear the high speed fan going when its only 7 degrees celsius outside.
 

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So after doing this mod, is the 2nd speed eliminated?
I desperately need to sort mine out, i've got all the stuff to do it but no time or daylight! I'll get stuck in one too many traffic jams soon and then i'll wish i'd sorted it!
 

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Doing this mod fixes the low speed problem.
So after doing it you get both low & high speed just like new.
Give it a go, not as difficult as I thought it would be.
If you get stuck in a jam its HVAC fan on full, dial to hot & drop the windows....and hope your heater matrix does not explode like mine did , twice!
 

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Dsjoe: Have you taken your feeds from the old (broken) resistor or cut into the wires around the plug as Chris suggests in his guide ?
 

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Discussion Starter #11
I really need to understand how the fan works and what relays etc are involved and when they come in.

I want to fit a NON OEM fan to the outside of my radiator - NOT repair the one I already have. Reason for this is simply for clearance so that I can fit a cast inlet pipe to my supercharger.

There are two relays under the bonnet in the fuse box marked as FAN I and FAN II
There is a fan relay in the box at the passengers feet

Is there a relay on the actual fan assembly too as well as the resistor?

I would have assumed that the three cables in the large connector block leading to the fan assemble were simply Ground, High Speed and Low speed.

But I understand that it isn't quite as simple as when the Low Speed is called on, the FAN I relay kicks in, when High Speed is called, FAN I knocks off and FAN II relay kicks in. But different things I have read say different things. Its starting to piss me off now that something so simple is causing me so much stress.

The road I use for my commute is now flooded so I have to go the long way round which has turned a 10 minute drive into a 50min journey in mostly standing traffic. Temps are not good!

Please can someone help?
 

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I understood that :-

when the Low Speed is called on, the FAN I relay kicks in, when High Speed is called, FAN I knocks off and FAN II relay kicks in.

As a short term fix I shorted the 2 under bonnet fan relays so that when the BCU switched on the low speed relay it actually also switched on the high speed relay and high speed fan came on.

Noisey but safer than nothing......
 

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On very early cars there is a relay next to the resistor on the fan unit.
later cars both relays are in the fusebox.
Mine is Nov 2003 and has the 2 in the fusebox...
will try and dig out the wiring circuit for the very early cars
Karl is your fan wiring R50 or R53?
 

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Just for clarification as i need to do this when my resistor turns up....

All i need to do is connect wires to each end of the resistor and then splice into the 2 red wires as per below picture and i will have a working low speed fan ??? ( And the high speed will kick in as normal if things get really hot )

 
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