Aux cooling fan power? - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 10 (permalink) Old 09-24-2019, 01:39 PM Thread Starter
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Question Aux cooling fan power?

I spent time Saturday working out why my 86 Quad's aux cooling fan wasn't running. A quick voltage check with a multimeter showed I wasn't getting power, but if I jumped the relay the fan would run (thankfully). After a bit of puzzlement, I traced the power lead back to the driver's side and found that surprisingly, the lead wasn't connected... and it looked like something was melted. This connector(?) looks like remains of some sort of fusible link, and apparently had been this way for a while given the corrosion of the remains. (Sorry, no pic--I can add one later.) For now, I made a connection to the power block and voila! I have cooling fan action for the A/C and at overtemp (tested with a lighter).

My question is twofold:
1) What was that thing?
2) Is what I did safe?

This is the last puzzle before I venture out on the road with a fully functioning cooling system.

Thanks,

Steve

1986 Spider Quadrifoglio "Lola", 1965 MG Midget MkII "Gidget", 2011 Mini Cooper S "Nigel"
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post #2 of 10 (permalink) Old 09-24-2019, 02:03 PM
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Pictures would help as far as identification goes.

Is there a fuse between the power and the relay? It should be a small amperage fuse. If that's in place it should be safe.

Chris

1990 Spider Veloce
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post #3 of 10 (permalink) Old 09-24-2019, 02:07 PM Thread Starter
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Chris,

Thanks for the quick reply. I'll post a pic tonight--I failed to snap one, but I have the remains on my bench. I guess it could sort of look like a fuse holder if you squinted at it right. There is no fuse at the moment (but I plan to fit one)--what amperage would be sensible?

Steve

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post #4 of 10 (permalink) Old 09-24-2019, 03:39 PM
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I depends on the exact relay, but usually 5A is sufficient for the trigger side of a relay typically used in an application like this. You want to pay attention to the wire gauge as well when thinking of these things, but 5A can safely go across a very thin wire.

Chris

1990 Spider Veloce
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post #5 of 10 (permalink) Old 09-24-2019, 05:49 PM
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From the wiring diagram, the fan pulls power from one of two relays: the cooldown relay and the aux fan relay. The cooldown relay is triggered by the temperature sensor on the shroud, and the aux relay is triggered by the A/C thermostat control.

Both of these pull power (at terminal 30) from a single red wire that runs from the aux fan relay to the junction box on the left fender. This wire should have an inline 20A fuse very close to the junction box.

So it sounds like you need to add a 20A inline fuse, as currently your power feed is unfused and a potential safety risk.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
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post #6 of 10 (permalink) Old 09-25-2019, 10:54 AM Thread Starter
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Hi Tom,

That makes sense. I will be installing a fuse. I am just pleased that the remainder of the system is working!

Here's a picture of the remains.

Thanks!

Steve
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1986 Spider Quadrifoglio "Lola", 1965 MG Midget MkII "Gidget", 2011 Mini Cooper S "Nigel"
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post #7 of 10 (permalink) Old 09-25-2019, 11:13 AM
But Mad North-Northwest
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My guess looking at that would be that the fuse holder built up some corrosion & had high resistance, and this caused it to overheat and melt the wires.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #8 of 10 (permalink) Old 09-25-2019, 11:24 AM
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I replaced my fuse holder with a waterproof marine one.

Richard
76 Alfetta GTV gone to rust haven, 89 Spider the red graduate, 86 GTV6 on wish list
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post #9 of 10 (permalink) Old 09-25-2019, 12:05 PM Thread Starter
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I just ordered one. Great suggestion. Thanks all!

Steve

1986 Spider Quadrifoglio "Lola", 1965 MG Midget MkII "Gidget", 2011 Mini Cooper S "Nigel"
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post #10 of 10 (permalink) Old 09-25-2019, 02:02 PM
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Oh I see now. Disregard my 5A suggestion - I misread and thought you'd traced the trigger wire through the firewall and under the dash.

Chris

1990 Spider Veloce
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