The AUSubaru.com.au Forums

As the title says, I've just discovered a problem with Sunnie's electrical system - once you've turned the lights on, high beam or low beam, the thermo fans cease operating Not good. I almost cooked him good last night.

I don't know how long this has been occurring. The fans will not work when at the temp that triggers the thermo fans via the thermo switch in the radiator, they won't work with the AC on and my switch to trigger one fan doesn't work either with the lights on. When the parkers are on it's all good same with not using the lights...

Any ideas on where to start looking for the gremlin that's responsible for this??

Cheers

Bennie

The fans are miswired. The slimline fan is supposed to drop out when you turn your headlights on. Not both of them.

phantomD wrote:The fans are miswired. The slimline fan is supposed to drop out when you turn your headlights on. Not both of them.

What's the reasoning behind this? I don't understand why subaru would cut one fan when the lights are on. I've never heard of a car company doing this.

Last night it was still 33 degrees in Benders, driving with the lights on cut the thermo fans and thus I almost cooked the poor bugger with all the stop start urban driving...

You wouldn't happen to know where the cut out for the second fan is in the grand wiring scheme of the MY's do you?

Cheers

Bennie

Are the lights dim?

Im thinking you might have a bad ground and the voltage drop of the lights is making the fan relay drop out. Have you tested the voltages at the relay?

My fans work regardless of lights on/off etc.

Both fans ??

The AC (and its fan) is usually an after factory install at the dealer or contractor installer/ after market and different power line. Mine has wire straight off the battery into a fuse holder with excess wirte tucked into a hole in the inner guard next to battery.

Gannon wrote:Are the lights dim?

Im thinking you might have a bad ground and the voltage drop of the lights is making the fan relay drop out. Have you tested the voltages at the relay?

Not tested the voltage at the relay, but it should be 12v as it is a direct wire from the battery (fused) to the relay, both fan and driving lights are setup in this manner, but that's the only common wire between the two of them.

The high/low beams are your usual stock subaru dullness. I'll check the voltage there too when I get the chance, currently against time with a bigger project.

steptoe wrote:My fans work regardless of lights on/off etc.

Both fans ??

The AC (and its fan) is usually an after factory install at the dealer or contractor installer/ after market and different power line. Mine has wire straight off the battery into a fuse holder with excess wirte tucked into a hole in the inner guard next to battery.

Yep, both fans Jonno. This could be because I've referenced my positive source for the switch from the AC system when the ignition is in the accessories or the on position, I should test the stock wiring for the fan to see if it continues to run with the lights on. The other thing I need to check out is that the AC is still operating when the lights are on, I'm pretty sure it does but not 100% on that.

Got some good ideas to lead on with fellas, thanks for the input

Cheers

Bennie

Quick update:

Ok so I've quickly checked out the AC operation with the lights on - the AC compressor is engaged and turning when the lights are on, fans still out of action.

Next is to test the voltages at those given points...

Cheers

Bennie

yeah, guess you need to tap into the fans power source with a light, buzzer, multi meter or 12V appliance - go through your test procedure and suck it!

Turn your lights off - the fans come back on immediately ??

A rewire may just fix rather than find the problem. A mate does this all the time, saw him do it with one injector not opening, ECU still trying to drive it so just ran a new bodgy wirte - fixed

PS :/ new emoticon ?

steptoe wrote: :/ new emoticon ?

Yeah, as ??? doesn't come up so well in the title...

Cheers

Bennie

Sounds like you've tapped into an earth and power feed (to run your fans) from your headlights circuit and when your lights are off, the power is there at the lights (and now to your fans) but doesn't go anywhere until the light switch is turned on and then when you flick the light switch on, it switches to earth causing the power to find the path of least resistance.

Hope this makes sense.. it does in my head but never comes out right when typing.

So both the thermos are supposed to remain on with headlights on? If that's the case then I have an issue.

Although we've already discussed in another thread that different air conditioning looms exist between early and later MYs.

Subaru do it different to most earlier model cars. Subaru supply power to the unit then use the switch to switch it to earth. PITA when doing anything like spot lights, horns, etc... Best way is to use a relay (using the coil pinouts) on the old Subaru wiring, then supply new power (with a fuse) to your new part, then to earth.


God I hate electrical wiring.. thankfully we have Dave

RSR 555 wrote: God I hate electrical wiring.. thankfully we have Dave

W.A. has Dave, East Coast has Jack

Jack S**t!

nachaluva wrote:W.A. has Dave, East Coast has Jack

Jack S**t!

Not true.. East Coast has Al from AMAutos

RSR 555 wrote:Not true.. East Coast has Al from AMAutos

Well played sir!

So what I'm thinking has happened is that the AC system uses the fan power switch to trigger it's relays, with out the cabin fan on there's no point in having the AC in operation.

Then there's the relay for the AC's second thermo fan - What I think has happened here is that the power source for this fan has been tapped into one of the wires you guys are talking about. AFAIK the MYs were still positive switching, not this uber confusing earth switching that the L series onwards does.

Now the reason why BOTH fans don't work with the head lights on is that I tapped my accessories power source wire for the new relay from the wire that feeds the AC's thermo fan relay. So with the head lights on I've managed to wipe out both fans from operating. My bet is that if I connected the original thermo fan back into it's original wiring plug it will still operate with the head lights on.

My idea to solve this problem is to find another accessories wire to the AC thermo fan's relay so that it solves both fan's issues when the head lights are on. Hopefully this will do the job.

Currently though I've got bigger fish to fry, it looks like we've got the very first signs of a leaking head gasket - it's all very confusing

Cheers

Bennie

El_Freddo wrote: Currently though I've got bigger fish to fry, it looks like we've got the very first signs of a leaking head gasket - it's all very confusing

Bugger! Hopefully its not a HG & its something simpler

nachaluva wrote:Bugger! Hopefully its not a HG & its something simpler

Well at 347k km on what we think are the original head gaskets I'm not complaining really, but it is something that I don't need to have on my plate at the moment.

Cheers

Bennie

I thought MYs were negative switched?

mutter,mutter,mutter - ambidextrous hermaphrodytic wiring in these Subies - all of them !!