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deMort
Shanghai


Joined: 21 Mar 2015
Posts: 4605
Location: Brighton


PostPosted: Mon May 07, 2018 7:10 pm    Post subject: How to check your fan resistors. Reply with quote

Youll need a voltmeter and a wire pierceing end .. if not then a small cut into the wires with a blade to access the copper.

You will need tape to seal the wires after so a probe is best .. see image .

Over view of the system ..

A/C turned on and the low speed fans will be operated , it doesnt matter if the a/c is out of gass .. the car doesnt care .. it will still increase the engine rpm and turn on the low speed fans .

Low speed fans will kick in reguardless at an engine temp of about 95 C .

High speed fans will kick in at an engine temp of about 105 C .

3 wires on the resistors ..

One goes to the fan motor
One comes from the Low speed relay
One comes from the high speed relay.

The high speed by passes the resistor in that steel caseing .. it goes straight to the fan.

You dont need to know which wire is which but there is a diagram below if you want to look .. dont help much as the colours of the resistor are white , white/green and green which it doesnt show .. lol .

Engine running , a/c turned on then check each wire for 12 volts .. if the resistor is working then x2 of the wires will have a feed and the fan will be turning ... if the fan isnt turning then you have a faulty fan motor.

A Failure of the resistor will mean you only have feed on x1 wire .. no output to the fan motor .

You can replace the resistor with non porsche that are listed in other posts .. perhaps someone could add a link here for me .

If replaceing with a Porsche one then you can either strip out the arch liner or you can cut and join .. soldering iron will be required along with heat shrink and tape .
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alex yates
Brands Hatch
Brands Hatch


Joined: 06 Mar 2014
Posts: 13299
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Mon May 07, 2018 7:25 pm    Post subject: Reply with quote

Ballast resistor:

https://uk.rs-online.com/web/p/panel-mount-fixed-resistors/0188071/?searchTerm=188-071&relevancy


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2000 Manual 996 C4 Arctic Silver Convertible

Used daily....rain, sun or snow.

 
  
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deMort
Shanghai


Joined: 21 Mar 2015
Posts: 4605
Location: Brighton


PostPosted: Mon May 07, 2018 7:32 pm    Post subject: Reply with quote

Blimy .. this post got very fat all of sudden Floor
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alex yates
Brands Hatch
Brands Hatch


Joined: 06 Mar 2014
Posts: 13299
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Mon May 07, 2018 9:51 pm    Post subject: Reply with quote

My fault mate, posting a mega long link.
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Jamesx19
Spa-Francorchamps


Joined: 10 Jul 2015
Posts: 283
Location: Brighton


PostPosted: Mon May 07, 2018 10:23 pm    Post subject: Reply with quote

Good post demort.

To get the correct reduction in fan speed (low speed circuit goes through the resistor) it needs of be about 0.5 K or 500 ohms

The other important thing is the power capacity of the resistor. The car only runs 12 volts, but even a draw of 5 amps will give 60 watts.

As per Alex's earlier post and link, that it the one you need. And a lot cheaper than a genuine one it is too....
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7582
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Mon May 07, 2018 10:23 pm    Post subject: Reply with quote

alex yates wrote:
My fault mate, posting a mega long link.


Very untidy Mr Yates Hand you can just post the first part of the link. (one of my editing pet hates, overlong links) frustrated
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mikealdren
Newbie


Joined: 06 Sep 2016
Posts: 10



PostPosted: Tue May 08, 2018 7:31 am    Post subject: Reply with quote

Jamesx19 wrote:
Good post demort.

To get the correct reduction in fan speed (low speed circuit goes through the resistor) it needs of be about 0.5 K or 500 ohms

The other important thing is the power capacity of the resistor. The car only runs 12 volts, but even a draw of 5 amps will give 60 watts.

As per Alex's earlier post and link, that it the one you need. And a lot cheaper than a genuine one it is too....


Hi guys,
500Ω or 500mΩ as per Alex's post? I think Alex is right, 500Ω would only need about 0.3W at 12V.

thanks
Mike
 
  
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Jamesx19
Spa-Francorchamps


Joined: 10 Jul 2015
Posts: 283
Location: Brighton


PostPosted: Tue May 08, 2018 9:06 am    Post subject: Reply with quote

Errr yep sorry math's wrong! 500 m ohms or 0.5 ohms not 0.5K!!!

Basically drop the voltage which drops the fan speed. Apologies for the poor post above.
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mikealdren
Newbie


Joined: 06 Sep 2016
Posts: 10



PostPosted: Tue May 08, 2018 3:22 pm    Post subject: Reply with quote

No problem, I just noticed the anomaly and thought I ought to warn the unsuspecting...
 
  
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alex yates
Brands Hatch
Brands Hatch


Joined: 06 Mar 2014
Posts: 13299
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Tue May 08, 2018 3:58 pm    Post subject: Reply with quote

infrasilver wrote:
alex yates wrote:
My fault mate, posting a mega long link.


Very untidy Mr Yates Hand you can just post the first part of the link. (one of my editing pet hates, overlong links) frustrated


Embarassed

I must not post mega long links, I must not post mega long links, I must not post mega long links, I must not post mega long links, I must not post mega long links, I must not post mega long links.

wack

Cheers Chris. Thumb
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