Mk1 Expert fan blower not working

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Wookey
(Donor 2019)
Posts: 253
Joined: 28 Dec 2004, 09:43
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Mk1 Expert fan blower not working

Post by Wookey »

So my fan blower has stopped working. It's mid summer and we're about to head to europe for a month. There is no aircon in this van so having the fan working at least is quite important.

It's a huge pain to get out (and I suspect even worse to get back in, with a set of not-very accessible clips and having to take much of the dash off to get at things.
Image

My real question is: how does the speed control work? It seems to be just a resistor from 0-500 Ohm (measured between fan control wire and earth) at the lever end, so is there a controller of some sort in the fan body itself?

Mine looks like this:
Image

As for the fan, It works if you put 12V on it, although I think not at full speed. But as soon as you connect the control wire it stops. Does that mean the fan unit needs replacing, or the dash slider or is something else amiss.
Image
(So it works like this - connect up that green wire and it stops)

The other really weird thing is that I don't have any power on the fan power line either. I can't find any blown fuses. The diagrams say F5 is the fan interior fuse (10A), but the _feed_ to that fuse has no 12V so the problem is upstream. Apparently this comes from a relay. Is that one of the two relays next to the interior fusebox (I have a small green one and big blue one)?

Seems unlikely that I'd get two faults at once, so I've quite confused abuot what's going on here. Knowing how it was supposed to work in the first place would help.
Wookey
(Donor 2019)
Posts: 253
Joined: 28 Dec 2004, 09:43
x 9

Re: Mk1 Expert fan blower not working

Post by Wookey »

OK. So I realised that I took of more of the fan housing than I needed to - the annoying clips could have stayed on - the blower unscrews from the cowling. Oh well. I don't have a haynes for this vehicle (there wasn;t one when I bought it, only Russek and Russek only deals with mechanical stuff, not interior bits.

I've bought a new blower unit as they are only 30 quid. But it has a 3-pin plug instead of a 4-pin:
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Old one on the left, new on the right

I only have 3 wires so it's probably the same electrically, but I don't know for a fact and I don't want to damage the controller by wiring it up backwards.
I could just hack the connector down and use that if I was reasonably sure this would work.
Knowing which 3 wires go to which pins on a Xantia (apparently the fan I have fits that too) would be very helpful.
I've currently got 12V in pin 1, controller wire (resistance to ground?) in pin 2 and Gnd in pin 3.

It would be really useful to know how these fans/motors/controllers work so I could work out what's going on. And it's all pretty urgent now as I'm leaving in 6 days.

I found one video online (Xsara Mk2) which is physically very similar but the controller and wiring is different: That's got a second connector and the driver transistors are visible.

My old controller is potted so I can't tell what the electronics does. Not checked the new one yet.
I presume the motor is AC or BLDC (it just goes 'clunk' if you give it 12V DC). So it's tricky to check which of the motor, controller unit, dash-speed-setter is at fault without knowing how any of them work.

Also, what is the name of these connectors - and is it possible to buy spares?
Image
It looks like it says 'RKG' on the right and I can't read the left logo. It might be 'SGE' in a diamond logo?
Wookey
(Donor 2019)
Posts: 253
Joined: 28 Dec 2004, 09:43
x 9

Re: Mk1 Expert fan blower not working

Post by Wookey »

Turns out the power wires for the 3-pin version are indeed the opposite way round to the 4-pin version. I can have full blast or nothing. Adding the 0-500ohm resistance to ground seems to do nothing on this one, so apparently it has a different control method too. Swapping it for a 4-pin variant tomorrow.

And I've worked after wasting an embarassing amount of time checking out wiring that the reason there is no power is that fan power is switched by the alternator D+ line so there is only fan power when the engine is on. Start the engine and power appears - so that was working exactly as intended. You'd think I would have noticed over 20 years of owning this van that the blower only works when it was running, but apparently it never impinged on my consciousness.
Wookey
(Donor 2019)
Posts: 253
Joined: 28 Dec 2004, 09:43
x 9

Re: Mk1 Expert fan blower not working

Post by Wookey »

This morning I got hold of the 4-pin version. And lo-and-behold, you plug it in, start the engine, and it all 'just works'. So the 3-pin version has both opposite power sense _and_ a a different control mechanism to the 4-pin (3 wire) version. Obviously!
Well that was a massive palaver, but it was indeed the blower controller inside the blower that had died. And a whole new blower is half the price (£33 (ECP) for the 4-pin one) of a replacement controller alone (£67 (ebay)).

So now I can drive across France in next week's heatwave (34C) with only some misery :-)

I'd still like to know where to get those brown connectors from, or at least what they are, because I've chopped one end off mine now.