LCR Fan Controller / Radiator Fan Fault?

[Gaz20VT]

Hi everybody,
Time to ask for some technical expertise regarding my LCR.

I noticed that the auxiliary water pump wasn't running when I switched the ignition on, or when I stopped the engine. So I checked out the wiring and looked to see if 12V was being supplied to the aux. pump - it wasn't. (I checked the pump with 12V direct feed and it's also not working, so that's being replaced too.)

So I ordered a fan controller unit - a Febi Bilstein one, as it was £30 compared to ~£165 from a dealer for a genuine one.

I have fitted it, but now with the engine running (cold) and the air conditioning set to "LO", the small fan pulses between full speed and off, whereas I'm pretty sure it didn't do this before.

So my questions are:-
1) Has anyone else used one of these Febi fan controllers before, and if so was it any good?
2) Do I have a low-speed-fan issue (as per the FAQ Section), or is it the fan controller?
3) Has anyone successfully fixed the aux. water pump circuit in the OE fan controller?

All help and guidance gratefully received!

 

[mty12345]

Hi mate, i don't have the LCR so not over familiar with the aux pump set up, however, i would imagine that it would only have voltage when ignition is off, and possibly only when the engine is off and also hot??? Like i said i'm not sure but it must be either time or temp controlled once the ignition is off, or other wise it would run constantly.

1) i don't know of anyone that has fitted one.
2) It sounds like it, although like you say i guess it could be an issue with the bilstein controller.
3) as above, are you 100% sure that you are testing it at the right time and it's not just the pump itself that has failed? Have you checked the fuse? ( i guess there must be one)

Sorry i can't be more help than that.

 

[Gaz20VT]

Thanks mty12345, I'm happy that the aux pump side of it is OK - the aux pump should run as soon as the ignition is switched on according to the factory service manual, apparently. It should also come on after the engine is switched off.

My main concern is about the fan speed - when I put the air con to "Lo", the small fan runs for about 30s flat out, then switches off for about the same time, turns back on, etc etc.

 

[mty12345]

Sounds very much like the slow speed issue to me mate.

 

[Gaz20VT]

Thanks Matty
Another question for those with LCRs - should both fans work together or just the small one for low speed?

 

[Alexis27]

Both together

 

[Gaz20VT]

Interesting. Going to start with a general wiring check first, then. I only have the small fan cutting in with the air con set to "LO".
Will post back when I figure out what's going on.....

 

[mty12345]

Have you checked the big metal fuses on top of the battery? The slow speed fan issue can sometimes cause them to blow...... I believe S164 is the large fan and S180 the small one.

 

[Gaz20VT]

So, to update this:-

I checked the fuses atop the battery, and they were all OK. I then removed the battery and checked continuity between 12V and the power supply terminal of the 4-pin connector (B) on the J293 fan controller. All good there.

This connector has 1 x 12V power input, 1 x small connector that connects to both low-speed fan wires, and 2 x large connectors, each one is connected to 1 x fan high-speed wire.

I checked continuity between each of the 3 x pins and their relevant fan connector at the bottom of the radiator.

So then I made a simple jumper connection, and systematically connected each terminal to 12V directly.

The only terminal that did anything was the high-speed side of the small fan. Small fan's low speed is inoperative (slow-speed fault as Matty pointed out above). This is also true for the large fan, but the high-speed side of this fan doesn't work either!

On the positive, the new aux pump arrived today and whirrs away nicely - and when it's supposed to!

So I guess I'm going radiator fan shopping, then!

 

[Gaz20VT]

Has anyone tried this:- http://pics.tdiclub.com/data/517/Fan_Repair.pdf

Does it work for our cars?

 

[Seatboy]

advice on the slow speed mod after cutting the red and white what do you do with the bit left over after cutting

 

[Gaz20VT]

I would cover the open end of the wire and secure it to the rest of the loom with a good covering of tape.

 

[Gaz20VT]

Faults Found!

Further update to this:-

I decided to investigate this a bit further last night, and eventually got the fans out.
Managed to remove them downwards through the engine bay by jacking the car up, removing the charge pipe between the coolers, undoing the small power steering pipe from the PAS pump, and removing the charge pipe bracket by drilling out the rivets!

Anyway, got the fans onto the bench:-

They are slightly different to the ones shown in the TDIclub pdf I linked to above. The bearing caps on these fans are held in just by staking of the rear cover, which is fairly easily undone using mole grips or large water pump pliers. There are cutouts to use for purchase. No grinding or cutting necessary.

The large fan has 4 brushes, of which 2 were stuck out of contact with the commutator, hence the open circuit and no fan operation. The large fan has metal brush holders, so by carefully bending the ends the springs can be removed. The brushes can be cleaned so they can move smoothly.

The small fan is similar but has a plastic brush holder. So the only thing I could do was blast the area with switch contact cleaner to remove the brush dust that builds up and causes the brushes to seize in the holders.

You can see the white plastic/ceramic moulded component, which is the slow speed resistor. On both fans, this was completely disconnected from the Red/White wire – possibly by overheating or corrosion of the joint and then the weak point acting as a fuse. This is the common Low Speed Fan issue.

The resistor is a concertina-shaped piece of resistance wire, whose resistance is exactly 1Ohm.
The white resistor is wired into the fans in exactly the same way as the Slow Speed Fan Fault fix mentioned elsewhere, they are just inside the motor bodies.

So I have ordered 2 x 1Ohm 100W resistors, and will see if these fans can be resurrected!

Hope this is useful for anyone else with the same issues.

 

[mty12345]

Good work stripping them down and finding the problems mate. All very interesting and i'm sure it will be useful to people with a similar issue in future.

Will be interested to see how you get on and if they work ok once repaired. Will be keeping my fingers crossed that all goes well for you.

 

[Battoussai]

Nice digging! Hope you'll sort that out. It will became a huge help for many.

 

[Gaz20VT]

Update time:-

Have finished the wiring for the fans, and got them back together.

Starting with the small fan, I unsoldered the Red/White wire from the board near the wire guide, and removed it completely.

I removed the old resistor from the motor completely.

A new loop of wire connects the Slow Speed wire to the motor brushes.

The new resistors arrived, and due to not having any other stainless hardware, I drilled the holes out to M6.

Then found a place I fancied mounting them. I want to keep the fan assembly as a removable unit, without having to run wiring all the way back to the battery area. If they get too hot and fail, I’ll move them.

Then I’ve connected the original Red/White wire to the resistors, using new cable. I’ve slid the new cable into the original black sleeve, using the space left by the original Red/White wire.

Some heatshrink keeps the wiring toether, so it can be secure in place later.

The new cable connects to the existing position on the motor base

Two holes in the shroud near each resistor allow the wire through for the connection. A tip, rebuild the fan motors before soldering the connections for the resistors…..!

The fan motor can be reassembled, and the wiring clipped back in to the fan shroud. A cold chisel can be used to re-stake the fan motors. A good tip is not to bend the tabs too much during disassembly.

 

[Gaz20VT]

The large fan gets much the same treatment, however with the different design of motor base it’s difficult to do exactly the same.
Here I’ve unsoldered the Red/White wire from the motor base, and the small screwdriver is pointing at the resistor connection, which is about to be unsoldered too.

I didn’t manage to replace the Red/White wire in the board, so I had to splice into the High Speed (Red/Black) wire. Apologies, no pics of this bit. Anyway, it’s an easy solder joint and I’ve then covered it in tape – I forgot to add the heatshrink on this joint.

The large fan gets re-assembled in the same way as the small one, and the resistor connections made and covered with heatshrink.

The only extra step with the large fan is to re-install the springs into the brushes and bend the ends of the brush holders back into place.

Three holes were drilled in the central divider of the fan shroud to allow the wiring to be secured with cable ties.

That’s where I’ve got to, next step is to re-install the whole lot into the car!

 

[ibizacupra]

those resistors will get mighty hot.... sat against that plastic....
ally plate to mount them to to heatsink advised

 

[Gaz20VT]

Thanks Bill, I'll try to find a suitable piece of aluminium and install it.

Interestingly, the data sheet on the CPC website doesn't give much info as to what cooling or sinking is required. The resistors are sat on M6 stainless plain nuts between the fan shroud and the underside of each resistor.

The resistors are rated for 100W, and so I decided to make a quick calculation as to how much power they have to dissipate in use.

Fan Motor Resistance ~1.5Ohms.
Low Speed Resistor 1.00Ohms.
Total resistance of low speed circuit = 2.5Ohms.

I am assuming system voltage of 13.6V.

Voltage = Current x Resistance
V=IR

I = V/R = 13.6V/(1.5Ohms + 1.0Ohms) = 5.44Amps current flow through the system.

The voltage drop across the slow speed resistor is a function of the ratio of the resistance of the fan motor and the slow speed resistor.

R1 (Slow Speed) = 1.0Ohms
R2 (Fan Motor) = 1.5Ohms
Vsupply = 13.6V (normal car running voltage)
Vmotor is the voltage available at the fan motor for low speed.

Vmotor = R2 / (R1 + R2) * Vsupply = ((1.5 / (1.5 + 1.0)) * 13.6 = 8.16V.

This is the voltage at the motor for slow speed. So we lose (13.6 - 8.16) = 5.44V over the slow speed resistor.

Using Power = IV we get 5.44A x 5.44V = 29.59W - just slightly more than 1 x indicator bulb. That said, I don't fancy grabbing hold of the resistors after they've been running for a while!!

I'll try to test the setup on the car, and see if any of the above holds true!

 

[mty12345]

Really interesting to see the repair mate. Should help a lot of people in future with the nice clear photos etc.