Ventilation fan has stopped

[HPsauce]

Originally Posted by HPsauce

Basically the Brown/Red Earth side goes to a major earthing point via the Blower Controller. Is that the "hedgehog" unit?

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.

[moltuae]

Originally Posted by HPsauce

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.

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.

[ainarssems]

Sorry Andrew about late reply.

VCDS scan failed on the HVAC module, too many communication errors.

Same here, it seems that it does not like low voltage as it's fine when engine is running or charger connected to battery.

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

It was a couple of years back so do not remember all the details but like everybody else said - rusted bolts and poor access.

Mine had commutator worn on one side so if it would stop with in a position where brush was touching worn bit it would not start again. Driving along it would move a bit either from vibration or air being forced through it by speed and start working again. Once it has started moving the momentum would get it past worn bit and continue to run but at lower speed as the part of turning angle there would be no current going through it. As the time went by the worn bit was getting bigger, speed slower and possibility of it restarting lesser. I am not a gambling man but considering your car has solar sunroof I would bet that it is blower motor that has worn out.

[HPsauce]

Originally Posted by ainarssems

I am not a gambling man but considering your car has solar sunroof I would bet that it is blower motor that has worn out.

Nor me, and I initially thought the same, but the evidence does somewhat point away from that. Not least because disturbing the connectors in the air intake plenum has effects.

For example, at the moment it is ticking over slowly with an overcast sky, no direct sun. Not been used for a couple of days.
If it was worn similar to yours I would expect it to stop on the worn section and not restart (especially with a low voltage solar input) without being disturbed, but mine seems different. Hence my suspicions of connectors/wires and damp/movement/temperature or similar factors.

I'm collecting a few cheap bits and pieces to enable me to diagnose it better. The whole lot will cost less than an hours labour at a garage so worth trying.

I've also been using the "REST" function as a handy test and noticed something about that; it limits the fan speed to 1, 2 or 3 bars only.
(I've never, ever used it and have anyway disconnected the auxiliary coolant pump)

[johnny_quattro]

I had a not too dissimilar experience with my blower motor. My car has the solar panel sunroof and has had the REST function disabled for 2-3 years after it started making the usual groaning noises. The blower motor started to operate in a rather feeble fashion about a week or two before it seemed to give up the ghost. I did jiggle the electrical connectors which had a small effect on the fan/blower rotation speed but nothing of any real substance. My fan/blower also occasionally demonstrated the same behaviour reported by Dezzy, in that the speed increased when turning corners.

The fan itself gave out eventually so I replaced it with a unit from our beloved forum's sponsors. I asked for a unit to be supplied from a non-solar panel equipped car, for obvious reasons. I would tend to agree with Ainars that it's probably going to be worth replacing the unit. I was told at the time that the fan/blower on solar roof-equipped cars always tend to stop working. I did inspect both units at the time and couldn't see a massive difference on the copper ring that is split into multiple sections (commutator.) I assumed therefore that the fan/blower had burnt out the brushes rather than the commutator.

[HPsauce]

A watched kettle and all that..... No problems whatsoever over the last few days. It knows I have all the bits now to investigate.

Currently I have two 4.2 V8 Audis on my drive with ventilation fans ticking over smoothly driven by a solar sunroof despite it being hazy/cloudy.
(My son's S4 is parked with us for a couple of weeks while he has some scaffolding on his house blocking the drive.)

[HPsauce]

Originally Posted by HPsauce

A watched kettle and all that..... No problems whatsoever over the last few days. It knows I have all the bits now to investigate.

And still working fine 2 months later.