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12volt three wire fan connections,

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C T11/09/2021 17:15:20
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43 forum posts
3 photos

I have just purchased two mini fans, these fans are used on VW T5 transporter vans to move warm air from the front of the vehicle to the rear. I would like to use them in a similar application but on a Land Rover Defender 110.

They have three wires and that has thrown me into a panic haw do i wire them up. The wire colours are RED, BLACK and PURPLE.

I have connected the red to a positive and black to negative on a car battery the fan dose not work.

Please help

Regards

CT

img_20210911_161630_6.jpg

David Jupp11/09/2021 17:46:40
784 forum posts
17 photos

Control = Violet perhaps ?

Control could connect to battery positive or to ground to turn fan on...

It could expect a PWM signal, or even an analogue variable voltage if variable speed control is expected.

Maybe check the wiring diagram of the donor vehicle for clues....

J Hancock11/09/2021 17:56:54
692 forum posts

I cannot see how you would do any damage by 'playing'' with combinations of the black/purple wires to the -ve.

It needs 12v 'difference ' across any circuit to make it work.

Howard Lewis11/09/2021 18:12:25
5224 forum posts
13 photos

Possibly a two speed fan.

One wire will be common, the others may connect to different field windings (Although likely to be a PM motor) to provide the low and high speeds.

Akin to the rear wiper motors that were used on some cars.

Howard

Michael Gilligan11/09/2021 18:21:25
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18702 forum posts
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Start here : **LINK**

https://www.ebmpapst.com/content/dam/ebm-papst/media/catalogs/products/Catalog_Compactfans_US_en.pdf

… and search for the word purple

MichaelG.

kevin laxon11/09/2021 19:57:46
7 forum posts

As far as I can tell: Red +ve,Black -ve & Violet is control voltage so will probably be PWM signal for variable speed or less likely variable dc again to change speed,I would think these are specificly designed to be controlled by the heating & ventilation ECU,incorrectly connecting this will allmost certainly destroy internal control electronics so tread carefully & make sure of connections before you try them.

Michael Gilligan11/09/2021 21:19:58
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18702 forum posts
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Posted by Michael Gilligan on 11/09/2021 18:21:25:

… and search for the word purple

.

Hint : All three ‘hits’ are on p186

MichaelG.

SillyOldDuffer11/09/2021 22:25:21
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7472 forum posts
1648 photos

The diagram at the end of Michael's link shows the simplest option is to run the fan at full speed by connecting black to negative and both red and violet to positive.

Dave

C T12/09/2021 17:21:51
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43 forum posts
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Thank you for your replies, I now have a better understanding of how the fan should be connected. Let me first describe my understanding from your posts and then ask another few questions just to clarify which direction I will be going.

My understanding is that the fan will work on a DC voltage from 9V to 15V and that is via the RED + and the BLACK – wires, the third wire PURPLE (VIOLET) Is a control wire and requires a + feed of between 0V to 10V to make the fan function.

I hope that's correct so far.

I know that 0V on the control wire and the RED and BLACK hooked up to the car battery gives no fan rotation (because I have tried it) but will the fan speed vary with voltages from 1V to 10V (I have the 0V to10V from the link given by Michael).

On the subject of the control wire and the 0V to 10V will the 10V be a maximum voltage if it is then would the simple solution given by SillyOldDuffer cause damage the board within the motor?

If it is the case that 10V is a maximum, I would need some form of regulator to limit the vehicle voltage to 10 volts.

I have in the past come across things like ballast resistors, voltage regulators and voltage stabilisers. I have done a little googling with the above and spotted a 10V voltage stabiliser used on car gauges for greater accuracy of the gauges. Voltage Stabilizer (148876J) (sngbarratt.com)

Would one of these on each fan serve the purpose to set a maximum of 10V on the control wire.

Currently I believe that running the fan at full speed will fit my application but if in practice I find I need to slow the fan speed or vary the fan speed would a potentiometer between the voltage stabiliser and the fan serve as a speed control. If it will what specification potentiometer should I use.

I hope I have not asked too-many questions and thank you again for the help so far

Regards

CT

Edited By C T on 12/09/2021 17:24:39

Edited By C T on 12/09/2021 17:25:40

John Haine12/09/2021 18:28:23
4093 forum posts
241 photos

You are overthinking this. If the maximum input voltage is 10V then feed the control wire from a potential divider with a 2.2 K resistor to +12V and 10 K to ground. This will give just under 10V on the control wire. Or use a 10 K potentiometer with one end grounded and the other connected to +12 V through a 2.2 K resistor, the slider on the violet wire for speed control. You won't need things like voltage stabilsers etc.

C T15/09/2021 18:18:10
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43 forum posts
3 photos
Posted by John Haine on 12/09/2021 18:28:23:

You are overthinking this. If the maximum input voltage is 10V then feed the control wire from a potential divider with a 2.2 K resistor to +12V and 10 K to ground. This will give just under 10V on the control wire. Or use a 10 K potentiometer with one end grounded and the other connected to +12 V through a 2.2 K resistor, the slider on the violet wire for speed control. You won't need things like voltage stabilsers etc.

Thank you I have purchased some Bochen 3296. W103 (10k) and it is working just fine.

Regards. CT

John Haine15/09/2021 19:30:20
4093 forum posts
241 photos

Excellent!

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