a couple of questions:
just had the car idling and decided to turn the fan on (it doesnt seem to auto-engage, should it?)
my R1 clocks always seem to say 'LO' and the water temp never moves from its lowest setting (40 degrees)
its never been driven properly on the road but its been held at 3000 for quite some time at the emissions test, and the pipes certainly feel hotter
than 40 degrees.
anyhow, i turned the fan on and it ran for about 5 seconds then stopped. Fuse #2 (Rad fan and ECU - 10 amps) had blown.
any ideas? the only thing ive added recently is the front indicators and they seem to work fine.
is it restricted to only being either the fan or the ECU? if so, how do i diagnose the ECU part?
mnr loom and R1 engine btw.
cheers!
Does it give the rating on the fan?
Does your fuse blow immediately? If so you may have a short circuit or your fan is pulling more amps than your fuse can cope with on start up.
If the fan runs for a while then blows the fuse, then you may be running close to the tolerance of the fuse.
My two 12" fans take about 7 amps a piece. Had to use a 20amp fuse, 15amps couldn't quite manage it.
I guess if your fan is drawing around 8 amps, then a 10 amp fuse may not be man enough.
Also I originally used an inline fuse holder instead of the spade type. The contact got very hot, so I decided to change to spade type. My fans no
longer blow fuses and the fuse is cool.
You really should have your fans coming on automatically if there is a thermostatic switch fitted. If they are not then check if you have one or if it
has become U.S.
I have fitted a manual fan switch on my dash as well as the thermostatic switch, just to be on the safe side.
Cheers
Dave
Hi Rog,
The water temp will take a while to rise and depends on where you put the sender. Is it before or after the thermostat?
The temperature of the exhaust will clearly be above the water temp throughout though.
The fan should auto switch but IIRC its around the 98-100 degree mark with the aftermarket rad switch. Mine refused to work until I swapped the wires
round on it, strange as youd assume its just a switch and would work in either polarity, might be worth a fiddle.
If you suspect the switch has failed, you can plonk it in a pan of boiling water and test it with a meter.
As for the fuse, I assume the fan hasnt jammed or anything? If not, and the fan side of the house looks fine, Id be looking for shorts on the wiring,
its unlikely (but not impossible) that the ECU is causing the fuse to blow.
Good luck
Rich
[Edited on 8/5/07 by RichieC]
I'd agree with what's been said previously- you have to get the rad quite hot before it triggers the switch. I'm always suprised how
much blatting it takes before my fan switches on (ie 10-20 mins idling or syncing the carbs doesn't do it).....
You could get a IR pyrometer off Ebay and monitor the switch body temperature. If it gets above the trigger temp (usually between 95 and 100) and it
doesn't switch the fan on you know it's knackered....
(you could take the switch out as mentioned and dunk it in boiling water- but it might mean refilling the coolant / rebleeding it)
If left idling for ages mine will get hot enough to trip the fan. My clocks read about 80° but the sensor is not exactly in the water flow. It takes
ages to get above LO but then my sensor, like the donor, is after the thermostat.
Fit a bigger fan fuse. Fans take a big surge to get them going then settle down to a low (ish) current. Fit bigger fuses unit it doesn't brake
anymore.
Is the thermostat housing earthed?
If this is where your temp sender is mounted you'l need to earth it in order to get a temp reading at your clocks.
Geoff
it wasnt an instant blow, it did seem to blow during the 'powering up' stage (the fan managed quite a bit of speed before stopping again) so
the extra surge might well explain it.
i've just popped another 10amp in and it seems fine again, but i will swap it for the next one up just to be on the safe side.
cheers all, now i've just got to work out why my seperate water guage doesnt move and the rad doesnt come on automatically.
it doesnt help when you never did the wiring in the first place.. 
20 or 30amps is normal for a lot of manufacturers standard fans.
We had the same fan fuse problem, I measured the current whilst triggering the relay, the current surges to about 12A for a second before settling
down. The 10A fuse was OK for a while but blew eventually (overheated and boiled over at garage whilst trying to sort out SVA emissions). Fitted a 15
A fuse and its been fine ever since.
Take the fuse out of the fusebox and use an ammeter where the fuse should be to see how much your fan draws when turned on - fit the fuse slightly
higher.
HTH
Ed
[Edited on 8/5/07 by esn163]
quote:
Originally posted by Peteff
20 or 30amps is normal for a lot of manufacturers standard fans.
quote:
Originally posted by Dillinger1977
cheers all, now i've just got to work out why my seperate water guage doesnt move and the rad doesnt come on automatically.
I'd go with the bigger fuse as mentioned before, a 15A will still blow easily ahould there be a fault.
For anybody having quite a few electrical problems that are hard to sort (I had a nightmare getting total closure to work on my tin-top)
There are mini circuit brakers available from maplins that possibly fit straight into the normal blade fuse terminals, or if not you crimp a standard
blade terminal to a short length of wire and then plug that into the fuse box.
They work on a themal overload and given a few min's they cool down and reset although there is no indication that they have tripped so I rigged
a little bulb up on the outgoing side to show when it was live and tripped.. useful little tool!.
http://www.maplin.co.uk/search.aspx?MenuNo=55418&FromMenu=y&doy=8m5
I've got a 20A fuse for my fan and it runs fine.
It takes about 5 minutes at idle for mine to get up to 70 degrees, that's using the sensor in the stat housing (2003 R1)
Cold weather running shows a constant 75-80 degrees, warm weather I may hit 90.