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-   -   D3 heater/ac fan problem (https://forum.a8parts.co.uk/showthread.php?t=15183)

mannyo 23rd August 2019 06:24 PM

D3 heater/ac fan problem
 
So, i guess as a result of lack of use my D3 heater blower has sort of stopped working.

Because the blower motor runs perfectly fine when being powered by the solar sunroof, I don't think its the motor itself.

So today I installed a replacement fan controller in the blower motor housing, and the result is still the same. Runs fine when left in the sun and engine off.

However today was really sunny and I discovered the fan is actually running with the engine on, but it's stuck in solar mode. Switching the system off and the fan still runs, disabling the solar sunroof running makes no difference and the fan continues to run.

So the blower fan is stuck in solar mode by the looks of it, is there a switching relay like on the D2?

I did having it running properly for a couple of days a few weeks back and it did work briefly this evening until I turned the climate control off and the blower would not switch back on when I turned it back on.

Manual fan speed adjustments make no difference, neither does setting Lo or Hi.

HPsauce 23rd August 2019 06:38 PM

On a D2 switchover to the solar panel driving the fan is controlled by the HVAC system; I can't recall if there's an external relay or the solar panel is just wired straight into the HVAC and it's switched inside.
(I ought to recall, I've messed with it and it is VERY simple)
I wanted my D2 solar panel to be disabled with a switch and in the end I did that by cutting it's "earth" circuit and looping it out to a switch I installed. If there had been an accessible relay I would have done something to that.
(Awaits more informed opinions...… ;) )
As for a D3 who knows?

mannyo 23rd August 2019 07:58 PM

I found a current flow document on here, it details J355 as the solar operation control unit and appears to reside inside the car headlining.

Also found mention of J126 where the supply from the roof appears to plug into. It is J126 which I have replaced (I think) this in turn is connected to the climate module.

It is worth noting that I replaced the part with a used one from a newer car.

Really stumped now, I'll have no job in 5 weeks and I have this car which is eating money I cannot afford to lose.

mannyo 24th August 2019 11:47 AM

I've hooked up VCDS and have this code regardless of which controller (old or new) is installed.

I did clear the codes, and it comes back with the other usual ones I have.

Worth pointing out the fan did run earlier with no problem.

01844 - Control Module for Fresh Air Blower (J126)
008 - Implausible Signal
Freeze Frame:
Fault Status: 01101000
Fault Priority: 3
Fault Frequency: 1
Reset counter: 91
Mileage: 271398 km
Time Indication: 0
Date: 2003.02.27
Time: 00:10:42

Freeze Frame:
Temperature: 23.0∞C
Speed: 0.0 km/h
(no units): 8.0
(no units): 169.0

Research suggests in the blower motor despite the fact it runs fine on solar, any thoughts.

I'll reassemble the car tomorrow with the original controller, and I'll have to sell it with faulty blower, i've had it with this car now. I cannot afford to fix it.

HPsauce 24th August 2019 11:53 AM

Chances are that on solar it's a fairly direct connection to the fan, with no speed control.
In normal use it will be powered via a speed controller, so it suggests the fault is in that system "somewhere".

mannyo 24th August 2019 12:07 PM

I've checked all the connections, and put a multimeter measuring volts and everything appears correct entering and exiting the controller. I've got ground, 12V coming in, I can see 4 volts coming into the same controller from the sunroof, its just weird and i've lost all patience and run out of money.

mannyo 24th August 2019 12:38 PM

here is a video I just shot, as you can see the blower works normally in solar mode.

https://youtu.be/CTd5gmO3vyg

There are no fault codes against the motor, just the control module.

mannyo 24th August 2019 12:47 PM

Just a thought does anyone have a J126 controller knocking around, that I can borrow. You never know but the used one I got could also be faulty.

I'll then buy it off you, if it works or return it.

Part number is 4E0820521

mannyo 26th August 2019 10:56 AM

Still battling on with this, took interior apart and checked connections behind climate module and all is good.

Tried swapping old and replacement J126, still the same.

I had a look at measuring blocks and things look wrong here.

Address 08: Auto HVAC (4E0 910 043 )

10:29:02 Group 044: Fresh air blower V2
0.000 A Current actual
0 h Solar usage
0.00 V Voltage actual
5.80 V Voltage specified

The voltage specified goes up and down with the fan speed selection, but actual remains zero.

Switch engine off and solar kicks in and fan starts, and will then stay on solar even with engine restarting although VCDS is reporting zero volts.

mannyo 26th August 2019 11:34 AM

Unlike a lot of other threads, mentioning lack of fuse 44 my D3 has one. Should have checked first before rooting around under the passenger carpet to discover mine is not there like in this post. http://forum.a8parts.co.uk/showpost....46&postcount=6

Anyway fuse was good, so now I am going to check the ground connection. Interestingly I removed the drivers side sill trim to get access to the grounds and now the car will not start either, and the starter is on the same ground point.

Another observation, with fuse 44 removed, I get 12V on one side of the fuse, and the voltage from the solar roof feeding back on the other side.

Another observation, with fuse 44 removed, the solar function of the fan continues to work and the fan spins.


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