A4 2.8 Quattro intermittent blower

[AndyMac]

Just when you need climate control the most, mine is starting to play up again! Had it all serviced last month, regassed & new heat exchanger (which was leaking). The blower is now playing up. Sometimes it's fine, other times it just doesn't work. The aircon/climate control is working fine as on the motorway you can feel the air is nice & cold. Checked the fuses first time it happened and they were ok, and after checking, the blower worked fine. If it isn't working I take the keys out wait a few minutes and start her up again and then it works!
It's a long shot but anyone have any bright ideas? Could it be a loose connection somewhere?
I'll take it back to the aircon specialist but it's just a pain as they'll want it for a few hours.

 

[excursion]

Sounds like it could be the speed regulation unit near the blower. It's bright red, secured by a phillips screw and will have a black/blue, brown and grown/green wire going to it. You'll need to remove the glowbox to get to it.

With the ignition on, hold down recirc and press the up arrow.

When you see 1C come up press recirc again - tell me the codes you get back.

 

[AndyMac]

It comes up with .0 whether it's working fine or not blowing. The climate control thinks it's blowing, and the relay by the fuse box clicks when you turn it on & off.

 

[AndyMac]

Well this is a bit bizarre, if I disconnect the fan and wire it up to the cigarette lighter it works everytime. Obviously only at max speed though.
I can't see how it can cut out, when it has got at least 10v going to it. I've wired it up to a 10v power supply and it works, so it is not a case that it needs 12v.
I'm confused.....

 

[excursion]

The speed regulator unit controls the current to the fan, so possibly one of the didoes is breaking down.

 

[excursion]

The regulator unit also earths the fan. I think there's either a bad diode in the pack or the current is being cut altogether.

 

[AndyMac]

Thanks Mark, I'll get one ordered and see if it does the trick. I've wiried in a by pass temporarily, so if it refuses to work I can disconnect the regulator and connect the fan to the cig lighter.
Thanks for your help.
Cheers, Andy

 

[AndyMac]

Thanks Mark, I'll get one ordered and see if it does the trick. I've wired in a by pass temporarily, so if it refuses to work I can disconnect the regulator and connect the fan to the cig lighter.
Thanks for your help.
Cheers, Andy

 

[AndyMac]

No, but I'll give it a go. Do you suspect the old favorite "earth problem" could be the culprit?

 

[excursion]

It's not likely mate, but it's easy enough to check just to make sure it's defiantely the speed unit /ubbthreads/images/graemlins/smile.gif

 

[AndyMac]

£72 plus VAT? Are they having a laugh?

 

[excursion]

scrap yard?

 

[AndyMac]

Can't be *****. Need it now in this heat so had to order it.

 

[AndyMac]

Luckily they shipped the wrong one, and the proper one was even more money. In the mean time the fan stopped working even off the cig lighter (which was my workaround, when it got too hot). Took the fan apart, and found that the brushes (the 2 sprung loaded metal things that feed the power to the commutator) were heavily clagged up (technical term).
Rubbed them down with wet or dry and cleaned everything with WD40. Hey Presto, blower all working again at zero cost! That's a first. Can imagine Audi would have replaced the entire fan assembly at about £400.

 

[excursion]

Nice work Andy! It could have got very very hard to trace if the blower hadn't done that.

 

[AndyMac]

Intermittant faults, don't you just love 'em?

 

[jdp1962]

Good result, Andymac.

 

[AndyMac]

Thanks everyone. Here's a pic of the fan regulator just for the record, although in the end it wasn't faulty.