Blower fan acting crazy - solved

[Sol]

So I posted about the weird fan behaviour I've had the last two weeks, when it gave up the ghost even faster last night than in the last two weeks, I decided to get it pulled out today and see what's what. Normally I got about 15 mins out of it, enough to get to work or to get home again. Last night it lasted 5 mins then died. This behaviour is down to the thermal cutout on top of the speed control resistor and seems to be caused by 2 issues, water ingress via rain into the fan duct rusting the fan bearings, the fan gets a bit tight and draws more current than it should be. Not enough to blow any fuses, but enough to get the resistor pack hotter than it should be.

Then the fan resistor pack started to swell up in my case at some point, which I am guessing is causing some of the windings inside to short over, causing the fan to vary in speed while running. Not sure about the jingling noises I heard (and the wife could hear too) as it runs pretty quietly in the house on test.

Removal of the fan and resistor:

It's in a really stupid place on the RHD cars, above the accelerator pedal and is a bit of a pig to remove. 

First, take out the lower trim panel, 3 pull out clips and a few lever clips to push and the bottom panel lifts away. Next, pull off the front trim panel.

   

It helps to take out the right-hand retaining screw for the dash frame (T20 Torx) to make it possible to get onto the front bolt holding the fan in by pulling the dash frame forward....it can't be removed without stripping a LOT of dash off so just pull it forward. The dash frame and the front fan bolt want to occupy the same place at the same time. There are 4 of these fan bolts, and they need a 5.5mm socket (luckily I have a Halfords advanced mini socket set with some very small and unusual sizes.

   

   

The accelerator pedal needs to come out, push up on the orange clip and then press the black part in below it, and slide the plug off. 3 X 10mm nuts hold the pedal to the bulkhead. If you don't take the pedal out, the speed control resistor can't be removed.

   

[Sol]

So next once the pedal is out, you have to push 2 rear clips towards each other on the back of the fan plug and push the plug away from the fan motor at the same time. The 2 prong fan plug is shown, and the white area is the rubber seal round the socket on the fan casing, where the plug is inserted or removed from.

   

Plug out. Lots of swearing may have helped.

Next once you have used a loooong extension and the 5.5mm socket and a knuckle joint to remove 4 x small self-tapping bolts, the fan is loose and can be jiggled out of place.

   

The resistor is directly above the throttle pedal pointing upwards.....needs 2 opposing clips pushed in opposite directions while pulling downwards to remove the plug - also needing the use of a flat screwdriver to lever it out. Comes out of this hole: (edit - remove 5.5mm bolt and slide the resistor firmly towards the door side to unlock it, the pull it out downwards, and the reverse when refitting before putting the little bolt back in)

   

Resistor is rusted badly and swollen. Replacement part number is 6480.55


   

[Sol]

Fan is a bit tight, not rattling but on test in the house it draws 7A (updated after checking with proper clamp meter and not the power supply display) and the resistor glows at 180°C on my thermal camera while running at speed one. This is why it was tripping out. Seems 8 years of sucking in rain water had gotten the better of it. The resistor has a big fat bit in the middle. Glows really hot there on the thermal cam when running....smoking hot. Rotten with rust too. The swollen side is not clear in this pic but could be seen sticking out quite clearly when holding the resistor pack sideways on.

   

Fan commutator and brushes are pretty good. But, the bearings are tight, and are sealed in with crimps and can't be gotten at without destroying the fan so it's a new fan instead, and a resistor.

Fan for manual AC is p/n 6441AS (same one as for no AC) and the resistor is p/n 648055 for both system types. Fan model is Denso with a white impeller. Denso part number: DEA07019

The 6441AR seems to be identical, not found out what the difference is, if any. Denso this time would be DEA07018

Equivalent parts: Febi 170360 which states cross reference to both Denso numbers and both Citroen numbers. So they must be the same in fit and function.

Tools: Torx 20 bit for screws, 5.5mm socket and double extension plus knuckle joint, and Scorpion panel removal tool:

   

   

New fan online plus resistor £150 but will call my local motor factors tomorrow to see if they can supply the parts before I splash out money on eBay.

Some vendors want close to £200 for the fan unit and most show the wrong unit for the part number. I've found the correct ones on eBay already but if I can get them quicker from my local guy then I'll go that way.

[Sol]

Under dash panel clips (Leatherman excellent for pulling these little buggers out intact)

   

Why the pedal needs to come out: (resistor above it) - doesn't look like they clash in the picture, but believe me, they do. The resistor is also held in place by a 5.5mm bolt like the fan is.

   

Should last a good few years once replaced. Not much fun at -2°c when you're going to work in the morning with a frozen windscreen and the fan decides it doesn't want to play any more.

[jj9]

Fan commutator and brushes are pretty good. But, the bearings are tight, and are sealed in with crimps and can't be gotten at without destroying the fan so it's a new fan instead, and a resistor....

So it turned out to be a standard resistor pack & not the alloy type.

Thought your problem could be the bearings, as mentioned in the other thread most fan problems are.

It's a long time since I stripped a blower fan but can you not get some oil onto the bearings somehow?  (you may have to drill a hole in the plastic to access the end bearing)
If you can run the fan up in the house you may be able to position the fan so that the oil is able to run into the bearings.

The last semi seized fan I worked on was about 7+ years ago, oiling the oilite bearings got it going and it's still working so it worth having a go at it. 


PS.
Not sure why you didn't carry on on the original thread Blower fan acting crazy  as it's the same subject and it gives the original thread a conclusion.

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[Sol]

Ah yeah, I was brain addled by last night. I'll move it later to the same thread. The fan doesn't make any noises running on the bench, at any speed but the current is enough to make the resistor pack glow orange after a while at speed 1.

The up and down speeds and noises in the van were why I thought it was a controller issue. A simple wirewound resistor shouldn't do that but I think now the windings in the resistor are touching and changing the resistance when hot, causing the swooping up and down in speed. I didn't run it for more than a minute in the house. Long enough to see the resistor act up so it makes sense now.

Catcar is to blame for the part confusion, it says I have the one with the transistor pack, but I actually don't.

I could oil it and see if the current draw comes down. I just can't be bothered with pulling it all out if it only lasts a few weeks with a new resistor but I have time to play with it after today, as I'm on leave for a few weeks.

I've merged the threads now. Initially I did it as a separate kind of how to rather than put it in the same thread, but if merging them makes it more joined up for reading from problem to solution then happy to do so.

[jj9]

You could post up the blower removal & replacement as a separate part in the Member Submitted Tutorials & How To's. 

I've had the same thing with catcar, even when you go from the build date it can still be wrong, not often but there are occasions.

The oilite bearings can seize to the shaft and spin in their holder if this is the case freeing them off requires the fan to be pulled apart, I've done this in the past on a "Nothing to loose" basis but that was back in the day when new parts were out of the question and all parts came from the scrappy!  

I appreciate the blower removal isn't a 5 minute job, so yes if the fan won't free off to an acceptable level and the current draw stays high maybe a replacement is the way to go.

I'm not sure what the current draw should be at the given speeds, so if you get a new fan & resistor maybe it would be worth while taking a few readings for future reference.

I did find the info below  which relates to a VW Jetta,  I would imagine the draw on most fans should be similar.  


Fan Speed           With Recirculation           Without Recirculation

4                              19.8 Amps                           18.0 Amps
3                              11.5 Amps                           10.8 Amps
2                              6.8 Amps                             6.5 Amps
1                              3.9 Amps                             3.8 Amps

( Link to source )



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[Sol]

Cheers JJ, that's a handy table. I'll take a look at the new one and see what it draws under all 4 speeds.

[Gryffindor]

Well done for finding the fault. I'd agree with jj9 that the fan itself is probably still serviceable and the resistor is heating up because it is fried, not because the fan is, but because of the amount of effort you've had to go though, it would be as well to put a new fan in anyway, if only for peace of mind. If the old one proves to be good, flog it on eBay!

[Sol]

Now that might just happen....hmm...good idea!