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Black Beauty
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| Posted: 20 November 2007 at 00:31 | IP Logged
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Its common for the low speed function of the fan to stop working therefore allowing the engine temp to run > 90 deg C
The 'LO-Speed RESISTOR' is located at the top of the radiator, nearest the battery
Try removing the resistor, check the connections & the resistance of it ... should be 0.3 ohmns
if it looks excessively burnt or shows an open circuit then replace it.
alternatively as a test try this:
1. car in netural, start the engine
2. leave the key at MAR position
3, disconnect the temp sender at the thermostat
4. watch the fan, after approx 2 seconds it should rotate at a low speed
5. after another 2 second sit should rotate at a much higher speed
if it only rotates at ONE speed then thats most likely to be the HIGH speed, confirming the low speed resistor is burnt out....
Edited by Black Beauty on 10 October 2008 at 10:39
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Chris155
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Most Technical 07, Most Helpful 08
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| Posted: 20 November 2007 at 02:04 | IP Logged
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*make sure the air con is switched off.....
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Gweg
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| Posted: 20 November 2007 at 13:45 | IP Logged
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*Don't panic if your engine management light comes on, it'll go away again after a few starts 
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2001 2.5 V6. 2005-2008
2000 2.0 TS Sportwagon. 2009-?
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daveg360
Membro Eccellente
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| Posted: 20 November 2007 at 14:03 | IP Logged
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When you 0.3ohms BB - was it exactly that? or is that the resolution of your meter? I can easily get a 0.22ohm resistor for a couple of quid - I wonder how much juice the fan pulls? I expect a 200w rated resistor would be fine though - the biggest twin fan setup pacet do, is ~183w
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Black Beauty
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| Posted: 20 November 2007 at 19:02 | IP Logged
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i didn't meausure  // thats the nominal resis valuve of it +/- ??%
the wattage is very important too .... a lesser resistance will make the 'lo speed' faster
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Black Beauty
Senior Alfisti
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| Posted: 10 October 2008 at 10:48 | IP Logged
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Coolant fan circuit diagram for a TS engine:
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gazza82
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| Posted: 10 October 2008 at 12:55 | IP Logged
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By jumping the connections to the resistor, you can force the fans to run on high speed only at both stages. Can only test if engine up to temp, but if the resistor has failed, this is an easy fix while waiting for the part as it means you have a fan. NOTE: When my resistor failed recently it prevented BOTH fan speeds from operating 
A short section of cable with two MALE spade terminals is ideal ... and small enough to keep in the glove box for emergencies.
Think I might start selling them as an "Emergency Fan Kit" for mega-bucks on ebay!! 
Edited by gazza82 on 10 October 2008 at 12:57
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Gazza
1998 156 2.0 TSpark Sportpack 2, sunroof, hi-spoiler, Alfa Rosso and V6 intake, clear repeaters.
If you're driving on the edge, you're leaving too much room!
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Alfa Romeo forum : Technical (156)
Topic: DIY low speed fan test.
