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Old 21st September 2020, 19:34   #1
richw
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Default Three (?) speed fan: a few Qs

Hi all,

My V6 75 is an 02-plate and was made in August 2001.

I noticed the other day when running the engine and a/c for a while, that the cooling fan comes on intermittently, and is quite fast and loud. Reading around some old threads, it seems that if you press 'demist' then you should get the fan running on slow (presumably the same as if the engine is cold and you put the a/c on?).

So I had a look in the front grill area for a resistor, and couldn't find one. So maybe I have a three-speed fan?

I plugged in TOAF and tried the fan speed test: 1 did nothing, but 2 and 3 did make the fan start for a few seconds. TOAF also showed me in the 'ZCS codes' section that '2-speed fan' was UNTICKED. This backs up my theory that I have a three-speed fan, and that speed one is broken. Does that sound logical?

What's the latest advice with a broken three-speed? Does everyone convert to two? Or are there new three speeds available? Or are repair kits viable? Some old threads I read were over 10 years old, so not sure how much still applies.

I'd appreciate any advice.


Cheers,
Richard.
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Old 21st September 2020, 20:05   #2
vitesse
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Not at all unlikely that you’ve got a 3 speed fan. Unusual to still have medium speed when the first speed goes as I believe they share a common earth.
If I remember correctly (I tested one yesterday!) Toaf will only run the fan for a few seconds even though there is a start/stop button, and you need the slider moved to the mid-way position.
New 2 speed fans are available, but I would advise you to open the fan motor and see the state of the commutator and carbon brushes. New brushes are available, and you might only have to replace one or two to bring the fan back to life. I’ve done about 8 three speed fans and brought 5 back to life, the others suffered from excessive commutator wear.

Good luck
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Old 21st September 2020, 20:30   #3
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Usually when a fan pulses on and off every 5 to 10 seconds or so it is a two speed fan with a failed resistor. BUT I have come across a three speed fan with a failed slow speed and working middle speed that presented the exact same symptoms.

Only sure way is to remove the bumper and have a look, a three speed fan has four wires entering the motor whilst a two speed has two.

If it is a three speed then as the second speed appears to work then it should be repairable with new brushes and if it is a two speed then it simply needs the resistor replacing for a gold one.

One final anomaly is I have come across two speed fans where the resistor is not fitted to the bracket on the cowling but hidden out of sight.

Hope this helps
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Last edited by stocktake; 5th October 2020 at 18:11..
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Old 22nd September 2020, 20:14   #4
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Cheers chaps. Sounds like I need to take the bumper of to have a proper look. I will have to try at the weekend and take plenty of pictures.

I am a bit nervous about taking a fan to bits. Some of the old threads sound awful! I would happily try it out on a spare, or even buy a refurbed fan. I will what I have got.
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Old 22nd September 2020, 21:15   #5
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If the fan isn't working correctly then what have you got to lose? Arctic's video shows you how to open it up: https://www.youtube.com/watch?v=ls1BJGxUoPo

Regards
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Old 23rd September 2020, 19:48   #6
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Thanks for the link.

I don't know how long the fan has been like this (maybe since I have had the car, 14 months). I have driven it plenty, so I don't see it as broken now. If I break the fan, then I won't be able to drive it, will I? I am probably just being a wuss.
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Old 23rd September 2020, 20:57   #7
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No particular reason why you should break it or cause any further damage if you follow Arctic’s guide. At least examining it will dispel the uncertainty. New brushes are available here: https://www.ecp.co.uk/rover75-carbon-brushes.php
Or if the commutator is worn beyond repair then there are plug & play replacement 2 speed fans on eBay.

Regards
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Old 5th October 2020, 18:01   #8
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Hmm, well... I finally got a chance to look. Front bumper off - seems just as faffy as doing the rear! I cannot see anything like a resistor, nor any markings which would tell me the type of fan. The fan is also obscured by bits and pieces of metalwork, and I was far too nervous to start stripping all that down!

I've also noticed this thread where rebrushing is mentioned and so is some sort of ultimate fan upgrade.

Mine is on 56k-ish miles, and I've no idea how long the low speed has been knackered. I've only had it about fifteen months, and it could have been broken long before. Eeek!
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Old 5th October 2020, 18:18   #9
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It is a bit daunting first time round, took me about 5 hrs, one almost 8 hrs due to rusty screws everywhere esp. the torx ones. The whole headlight panel needs to come off but it’s a good time to deal with any sharp edges, and lubricates the bonnet catches.
I think you’re referring to Jules’ fan upgrade, no doubt a good one but requires modifications. Whenever I’ve found the fan motor too far gone I’ve purchased the new 2 speed fans on eBay which require no modifications and are plug & play.
There’s only one way to find out and that’s to remove and open your existing fan motor, one way or the other it has to be done.

Regards
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Old 6th October 2020, 08:55   #10
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Quote:
Originally Posted by vitesse View Post
If the fan isn't working correctly then what have you got to lose? Arctic's video shows you how to open it up: https://www.youtube.com/watch?v=ls1BJGxUoPo

Regards
Never seen this nor the links before - as usual with Arctic, great shortcut for fixing a common fault with high 'milage' fans.
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