[alfa] Re: Fan switch issue

[C2slayman@xxxxxxx]

George,
    Another possibility is that the thermal switch is defective.  You didn't 
mention if it's an aftermarket switch or the stock GTV-6 switch that goes in 
the radiator, but I don't think it matters.  The switch is supposed to short 
when it gets hot enough (say 210C), but not go open until it gets cool enough 
(say 190C).  These numbers aren't exact, but you get the idea.  You might want 
to put the switch in a pot of water with a thermometer and an ohmeter hooked 
up.  Heat it up and see where it closes.  Then cool it down and see where it 
opens.  There should be a broad enough temp range to prevent the fan from 
constantly cycling on and off. 
    Hope this helps.

Charlie


In a message dated 8/20/2004 10:23:09 PM Pacific Daylight Time, 
owner-alfa-digest@domain.elided writes:
Date: Sat, 21 Aug 2004 01:11:44 -0400
From: "Brian Shorey" <bshorey@domain.elided>
Subject: RE: [alfa] Fan switch issue

> Here's a strange one. On my GTV-6 even with a new thermal fan switch
> installed, the fan cycles on-and-off so quickly that the engine runs
> very hot. With the thermal switch bypassed by a jumper, so that the fan
> runs all the time, the engine remains cool. There is nothing in the
> circuit but the fan relay and the switch, but the relay is in use
> whether the thermal switch is in the circuit or a jumper is in it's
> place. Why would the thermal switch make the fan cycle on and off (it
> only stays on for about 10 seconds before it cuts off, then it starts
> up again as soon as the blades stop turning and runs for another 10
> seconds) even when the temperature gauge on the dashboard says that the
> engine is so warm, the fan should be running constantly? BTW, the
> radiator and water pump are both new as of a little over 5000 miles
> ago, the cooling system's been bled, two thermal switches have done
> exactly the same thing, and the problem started out of the blue after I
> had the engine cleaned a little over a week ago.  I've got to say, I'm
> puzzled with this one. Any suggestions will be greatly appreciated.

This does sound like a puzzle.  The only thing that comes to mind is perhaps
there is some corrosion in the fan connectors, or the ground?  Perhaps the
increased resistance is causing enough problem that the switch doesn't
function correctly?

I'd try pulling apart all the electrical connectors, and the fan ground, and
clean and detail them all.  Beyond that, I'm not sure I could put a finger
on anything that would explain the behavior you're observing.

bs
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided