jabbahutt
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 posted on 11/8/08 at 07:07 AM |
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cooling fan overide
Morning all
Well got the battery problem sorted from of all places Costco.
Fitted and all seems well except for the electric cooling fan. For some reason it only works with the engine running. Before my battery fiasco it
worked fine with just the ignition on but now unless the engine is running the relay clicks and the fan only spins for a couple of revolutions.
What on earth could be causing this? I'l be the first to admit that the electrical side of things is baffling me but I really don't even
know where to start checking this particualr problem.
I know that I'll only need the fan with the engine running so I should be happy that I can't do anything daft like leave it on but
it's bugging me that it did work as planned and know it works differently.
Any pointers much appreciated.
Thanks
Nigel
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02GF74
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| posted on 11/8/08 at 09:37 AM |
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I think we need to see a circuit diagram.
It is fine to have the fan running with igntion on but debatable whether you want it running with igntion off.
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britishtrident
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| posted on 11/8/08 at 10:15 AM |
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Normal tin top way is for the electrical feed to the fan thermo switch permanently live --- so it works even if you don't have the key in the
ignition.
The reason is that if the engine is very hot heat transfer still occurs between the cylinder liners and the coolant ie the engine can start boilong
afer it is stopped.
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Hellfire
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| posted on 11/8/08 at 10:27 AM |
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Ours has two feeds - one for switched live (ign) the other is permanent live - I hijacked the permanent live to a dash switch so's we can
manually have the fan on permanent for track days.
Sounds like you have gone awry with the live/earth feeds on the relay.
Steve
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saigonij
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| posted on 11/8/08 at 10:37 AM |
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really need a circuit diagram from you before any guess work can begin.
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jabbahutt
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| posted on 11/8/08 at 12:40 PM |
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just tried uploading jpeg to my photos but got a syntax error
basically fused supply to pin 30 & 85 on relay
pin 86 to both rad switch and overide switch both then going to earth
pin 87 to cooling fan and then to earth
[Edited on 11/8/08 by jabbahutt]
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02GF74
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| posted on 11/8/08 at 01:03 PM |
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^^^ that circuit description is correct..... but we know it was since the fan is running. we need to know how the alternator and battery fit into
this circuit as the problem seem to lie there.
from the problem you describe, it does sound like the battery alone does not have enough oompf to turn the fan which is hard to believe.
so try:
1. disconnect fan from relay and replace with an indicator bulb - does closing override switch light the bulb and is it bright? this shows relay is
operating.
2. disconnect fan from relay and connect to battery positve (beware you will get a fat spark but that is normal) - does the fan spin at correct speed?
this shows battery has the oompf.
3. is the relay new? is it correct amp rating? (you would be looking at at least 20 A. Maplins sell 40 A relay for £ 2).
4. do you have cables of sufficient current carrying capacity for the fan, and for pin 30 off relay.
it all seems a bit weird ......
[Edited on 11/8/08 by 02GF74]
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