Ventilation fan has stopped (sometimes, not always!)
 

Not working at all, either with ignition or driven by the solar sunroof. :(

Looking in the manual there's a reference to a 40A fuse but the location is not at all clear (nor if I have a spare!)
(Standard type I have spares up to 30A but is this a different type?)

The manual says "There is also a 40 amp fuse for the heater blower in the electronics/relay box under the carpet in the front right footwell. In right-hand drive models the 60 amp fuse for the radiator fan is also accommodated there".

Does this actually mean the front passenger footwell, i.e. front left on a RHD car? :Confused:
If so, does anyone have a picture to show the location, or is it obvious once I dive in? (under my nice new board supplied by Sean last year +++ )

Edit: As noted later in the thread, sometimes it works, this is not a total failure.

I've never had to change/check that fuse but it does seem to be in the passenger footwell, according to this pdf (position 7, S25):
Attachment 16597

It might be visually obvious if it's blown. Otherwise I'd pop it out and check it for continuity.



http://forum.a8parts.co.uk/attachmen...1&d=1500989945

http://forum.a8parts.co.uk/attachmen...1&d=1500989945

Thanks Mark, found what I think is it mounted with a type 204 relay; looks OK, tests OK. :(

Found the same type of relay in the bottom row, left hand side (horn I think). Swapped them, no change. Not looking good. :(

All suggestions welcome as to what to try next. I'll do a VCDS scan but suspect that won't show anything.

Might just be corroded connections at the blower end.

I've never had a problem with the blower yet (touch Myrtle) so I don't know how easy it is to get to the connector (blower is just at the rear of the engine bay, is it not?). If it's easy to access I'd get a meter on the connector next ... see if you get a voltage there.

VCDS scan failed on the HVAC module, too many communication errors. Everything else is fine. :Confused:
Controls seem to operate and I can hear flaps moving, just no fan....

It's very common for the shaft sleeves of the fan to get clogged up with carbon from the brushes.
You can often get away with a clean of the centre housing.

Tapping it may give you temporary relief, or try manually ramping the fan speed up to full and see if it will go doing that.

Easy to get at fan, it's the first thing you come to under the fresh air intake grille and shut off flaps.
Good write up on Audipages for fan replacement, take the procedure as far as required...

I've taken the mesh cover off and with the intake flaps open (they close on recirculate) I can see two connectors, one pink and one beige. Both have at least one seriously thick cable in them.

My suspicion is that one relates to the auxiliary coolant pump and the other to the blower.

Based on this rather old post by me (about my PF in 2011) I'd say the pink (purple?) one was the pump and beige one the blower:
Note that on the FL model there is only one connector (beige/yellow) visible by the pump and to disconnect the pump I cut (and insulated) the relevant wires; I suspect the connector has just moved a few inches so is less obvious/accessible.

It does look like it's the beige connector, judging by images such as this: https://i.imgur.com/5bmLvyn.jpg

If that connector is clean, perhaps try giving the blower a tap/spin as Marty suggests. Brushes certainly sounds a plausible explanation. If it starts working after giving it a nudge, I'd suspect warn brushes is your problem.

Indeed it does, and we have lift off! +++

While you were posting this I took the intake mesh cover off again and tried to work out which was which then attempted to access the beige one.

As I tried to pull it from it's retaining clips I heard a very slow gentle soft thud. The blower motor ticking over extremely slowly driven by the solar panel.

And sure enough a bit of wiggling and it got a bit faster. Into the car, ignition on and we're blowing again, a bit hesitant but the problem is identified.

Thanks very much for the information and suggestions Mark. I now need to undo that connector and make sure it's clean and making good contact. :D

PS In case anyone has the noisy coolant pump issue it looks like the pink/purple connector in there is almost certainly the one to undo to disable the pump. :cool:

Well, I really don't understand this. :Confused:
Opened up the connector, all looked good, joined it up again and nothing.
A bit of wiggling, still nothing, then just moved it a bit to try and prod the motor and suddenly it's all working. :tuttut:

Currently it's back in it's mounting clips, appears properly joined, and is all working OK. Trouble is there's almost no slack to work with and just a small gap through the intake flaps to work in.

My suspicion is that somehow one of the (thick) cables isn't terminated properly onto the contacts inside one half the connector as the mating surfaces look fine.
I think I might buy a connector pair, make up a short lead to bridge the two halves and try to work out which side is suspect.

You could try squashing the pins (very slightly) too to make them a tighter fit. Had a similar problem with my washer motor recently. The connector seemed fine and it worked again when I dismantled half of the car to get to it. Put everything back and the damn thing stopped working again. After stripping the car down again I found that wiggling the wires didn't affect it but pushing on the connector did. So I gave the pins a light squeeze with long-nose pliers and that seemed to fix it.

Failing that, it's probably a bad connection where the wires attach to the pins, as you suggested, but it should be possible to determine if it is that by wiggling/pushing/pulling them.

I've already done what I can to tighten the pin/contacts.
Lobbed an email to our sponsors to see if they can supply a pair of connectors (ideally with pigtails) so I can test/experiment a bit more and decide what exactly is giving an intermittent connection.

I guess it could even be at the motor end, which would be beyond my personal capabilities I think.

If you can't get the connectors, to save cutting wires you could make up a couple of connector 'bypass' leads using 'bed of nails' test clips to determine if the problem is at the connector or the motor.

http://www.ebay.co.uk/itm/1pair-Angl...-/281896808055


http://uk.rs-online.com/web/p/products/7148281/

Thanks, I have quite a few ideas on how to bypass the connector, but those look handy. ;)
I do want to avoid cutting wires if at all possible as they are already pretty short.

It might as well be blower motor gone. Quite common in cars with solar sunroof as it's working overtime. When mine went it would sometimes work , sometimes not and if you hit near it or went over pothole it would start working again. Eventually it got slower and more non working than working. I was hoping it's just the brushes worn but turned out that while brushes were low it was mostly due to slip ring/commutator wear so I got replacement from A8parts. I did ask them for one from a car without solar sunroof and the one I received was very good condition with minimal wear.

If it is, how easy is it to replace?

I actually fitted a cutoff switch on the solar panel circuit to stop the constant tickover of the fan unless I wanted it on, though it had many years before my ownership.

I've just done one. Not easy at all, although I had the engine out which helped considerably! :D

2 challenges:

1, two of the screws for the blower cover are underneath the rear section of the airbox under the windscreen cowl. You can't remove this section with the blower in place, but you can't get directly to the blower screws with this section in place. I have a tiny ratchet which takes screwdriver bits which allows me to get to these two screws from the side instead. If you don't have such a thing then a flexible screwdriver might work. Failing that, remove the wiper mechanism and then you can detach the rear section and it will move about just enough to get a long straight screwdriver in, assuming the screws are in good condition. To remove that section with the blower in place you need to either remove the brake servo or the electronics box and aircon pipes. Utter madness.

2, in every D2 I've worked on 95% of the screws in the airbox are rusty stumps due to it sucking in our nice damp atmosphere. It takes a lot of patience to dig out the phillips-slots in the screw heads and then still many of the heads snap off when you finally get a grip on them with a screwdriver. A good pair of mole grips works for some of them, but access is difficult to most.

A brand new blower is just shy of £300, but remarkably in UK stock so available next day. I always keep a dozen of the little screws on hand so I can replace whatever does come out with new.

If it does turn out to be that I might ask you very nicely and have a trip down to Devon.......

I can attest to the aircon airbox screws being completely rusted. Already snapped head off one. And this is on a car that lived in Germany. Why didn't they use stainless or anodised screws the cheapskates?
You may want to try mixing up a solution of acetone and vegetable oil (from the supermarket). Around 50/50. It makes for a very good penetrating oil. Leave it soaked for a few hours then it may reduce the chance of those screws snapping.

Thanks for that, especially the Audipages link, missed it yesterday. :o

The Audipages write-up doesn't make it look too bad, though there is no mention of rusted screws there..... :rolleyes:
And they do seem to have a special tool, similar to what you describe, to get at the awkwardly-located ones. :cool:

I guess with the engine out you can get right up to it quite easily.

I'd be interested to hear how Ainars got on when he did it. ;)

As an aside, I also notice that the black foam around the outside (that seals against the bonnet) is falling apart, I even got bits of it blown into car during testing. :(
Is this a "thing" that's worth buying (if available) or would any decent foam of suitable thickness do?

I replaced my foam shortly after buying the car.
Readily available from Audi.
Part number 4D0820513A.

I'm personally tempted to take a look at generic auto rubber supplies to see if there's a suitable rubber seal to use instead. Probably pointless, as I reckon the seal weakness is at the sides anyway...

The fan has behaved very oddly over the weekend, sometimes working and sometimes not. And turning the speed up to max makes no difference at all, it just seems to decide to work, sometimes mid-journey :Confused:

Just been out to the car, it's pretty thick cloud at present, and the fan is just ticking over slowly driven by the solar panel.
IIRC that's driven directly with a relay that switches over to HVAC control/power when the ignition is on.

My thinking is that if it was the fan bearings or motor that are at fault then a low voltage input from the solar panel wouldn't make it work at all (and a high fan speed setting might prod it into life), so my suspicion still currently is focussed on the connector/wiring and some sort of poor/intermittent contact.

Currently awaiting some "bits" from A8parts that should assist with diagnosis. :cool:

Motor speed controller?

It fails equally on solar or HVAC control (including REST) so has to be something pretty fundamental/simple.

To clarify: What I meant was that if it's not turning over changing the fan speed (applying higher voltage presumably) doesn't kick it into life.
If it IS working the controls all act as normal.

I did mine too my motor would pick up speed cornering, rusty screws 4 of them snapped off i think. Removed the awkward ones with a bit in small ratchet. Replacement motor from A8Parts and asked for one from car without solar.

Linky to previous post

Ah, did you mean the thing, mentioned here as hedgehog-like? http://forum.a8parts.co.uk/showpost....35&postcount=5
I didn't even know it existed though I had seen the cooling fins. Is it directly in the circuit to the motor (I would assume not) or "just" another input to the HVAC system?

PS. Just been out to check today's status and I can hear the fan ticking over nicely driven by the solar panel.

I've ordered some generic weatherproof foam strip, 19mm wide and 10mm thick.
Three metres for a fiver, delivered. Should allow a few replacements if needed.

Very useful attachment which I've been studying. Thanks Mark (moltuae). +++

As far as I can see the main power wiring for the fan is "relatively" simple, though there are some additional thin wires to control units that are probably signalling/sensing in function.

Basically the Brown/Red Earth side goes to a major earthing point via the Blower Controller. Is that the "hedgehog" unit?
And the Red/Black Power side (up to 12v) comes via the fuse and solar panel relay.

Now, I have noticed the recirculation flaps are sometimes closed and reluctant to open, though haven't yet detected any pattern to this. Does this give any clues?
(I do normally use automatic recirculation to limit external fumes etc. but have now turned that off.)

All normal this morning though, fan ticking over gently in the weak sunlight.

That sounds about right looking at the wiring diagrams. And the J126 control module does appear to have a hedgehog-like heatsink attached to it. Searching online, it seems the J126 control module is common to a lot of VAG cars, with some people reporting similar faults. The design and part numbers seem to vary from one vehicle to another but it's possible they share some internals (and therefore problems). I found this D2-specific post:
https://www.justanswer.com/audi/2jzi...sn-t-seem.html

Studying the diagram, it looks like the 12 volt feed comes via the J309 solar relay and the S25 fuse. The relay appears to be a change-over, switching between battery and solar power. I suspect it's activated when on battery power (supplying power to the blower via the normally open contacts) and deactivated on solar (supplying power to the blower via the normally closed contacts).

The J126 module appears to control the voltage to the blower (and therefore the speed) by introducing ground resistance. Judging by the size of the heatsink and the simple 3-wire connection, presumably it's little more than a high-power bipolar transistor. If that's where the fault lies, being intermittent in nature, I'd suspect a bad internal or external connection. Since it's dissipating a lot of power and probably getting hot-cold-hot-cold a lot, I'd suspect solder fatigue. If it comes apart easily, check for bad internal solder joints.

Another suspect would be that J309 relay. You could take it out and try bridging the N/O contact wires (red/green and red/black). Don't bridge them with the relay in-situ though, there's a danger that might send power back to the solar panel.

Thanks Mark, it's not the relay though; as noted in an earlier post I tested that by swapping it with an identical one that IIRC controls the horn.

Having looked at the wiring diagram I now suspect that the other (black, 3-pin) connector in that intake area is to the "hedgehog" (not the aux coolant pump) so I'll have a play with both in due course.

I'll have the cover off in a day or so when my replacement foam sealing strip arrives. ;) That will be a good time to investigate; first test will be a direct 12V supply to the fan, bypassing that J126 module.

Part number 4D0 820 521A. ;) New ones are silly money (hundreds of pounds). :eek:
Found one really cheap online in Europe and ordered it, if nothing else I can use it for testing by swapping the plugs over; no need to mount properly at first. :cool:

You could also diagnose it with a volt meter. If you put the meter across the motor first, that'll rule in/out a motor problem. Running normally, I'd expect to see a voltage that changes with fan speed. When the fault occurs (ie fan not running when it should be), 12 volts would suggest a motor fault and 0 volts a controller/power fault.

If the first test suggest a controller/power fault, attach the meter's ground to a permanent ground connection (leaving the positive wire on the motor's supply connection). Running normally, you should have 12 volts. When the fault occurs if you still have 12 volts the problem is with the 'hedgehog' (or associated connections), if you have 0 volts, the fault it with the supply.

Thanks Mark, I like the logic, but it means hacking into cables or connectors to get readings and it's all weatherproof connectors in that area, so I'll try the "plug and play" option first.

I'm guessing that the thin wires running off the thick power feeds near the beige connector are probably to measure the voltages as part of the HVAC control system and the extra yellow/red wire is a control signal to the "hedgehog". I would presume it's fins are purely for cooling what is effectively a variable resistive load.

That would be my guess too. The yellow/red is definitely a control wire. If the controller is a simple high-power bipolar transistor, you'll probably see a voltage on that wire that varies with fan speed (probably 0-5 volts). There does appear to be some feedback/sensing connections too which may account for the remaining thin wires.

That's where the 'bed-of-nails' croc clips come in handy :)

Though studying the wiring a bit more there is a separate Earth to the solar panel wiring, meaning that (if my interpretation is correct) the "hedgehog" is bypassed when in "solar" mode. Logical.

That doesn't mean that the black connection in the air intake is irrelevant though, I don't know where that Earth lead splits off, it's still fairly big - 2.5 vs 5.0 for the main leads (minor ones are much smaller) and isn't in that connector.

Probably got a fixed high-wattage resistor in there somewhere if it does, to set the solar-powered fan speed. Since your fault occurs in normal running mode too though you can probably rule out a fault with that resistor or associated wiring.