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| D3 - Interior Electrics Airbags, Sensors, climate modules, instrument clusters, switches etc |
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#1
29th August 2015, 07:54 AM
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Weird HVAC issue
Here is a strange one, had it a few times over the last couple of months.
Sometimes the HVAC develops a mind of its own, take yesterday for example. Driving up the M3 towards London with no problems, then suddenly the system increases fan speed to guesstimate 3/4 and 15 seconds later drops back to normal. Repeats over and eventually stops after 10mins. Whilst the fan speed is at 3/4s and you press the HVAC off button, the HVAC switches off but the heater fan continues to run at 3/4 speed almost like the fan is getting power from another source since the HVAC off should have stopped the fan. I can get the system to restore normal behaviour if I hit the off button whilst the fan is at normal speed and then switch it back on again. No faults in VCDS, so I am guessing relay or something. Not sure how its wired, but could the solar roof relay cause this. Last night it was almost dark when this happened, so not sure.
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Manny 2004 A4 1.8T Sport Cabriolet, 89K Miles Past 2004 D3 A8 3.7 Quattro, Xenon, Bose, Blinds, Solar Sunroof, TV, ACC, phone and almost every option. 168K miles rising slowly with retrofit AMI and DVB-T in place of Analogue 2003 Volvo S60 D5 SE Manual, 197K miles. 2001 D2 A8 3.7 QS, Bi-Xenon, Bose, Blinds, Electric Everything, retrofitted RNS-D, 191K Miles 
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#2
29th August 2015, 09:29 AM
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There is a blower motor control unit 4E0820521
It might be worth looking into that or looking for a reasonably-priced replacement and just swapping it. The blower motor plugs into it - it is about a foot away looking at the cable. I seem to recall seeing it when I changed the pollen filter as I remember those copper coils. Last edited by snapdragon; 23rd April 2020 at 08:19 AM.
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#3
1st September 2015, 04:15 PM
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Good call, its the only thing I can think of causing any issue. Did it again last night on the way from Herts back to Dorset.
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Manny 2004 A4 1.8T Sport Cabriolet, 89K Miles Past 2004 D3 A8 3.7 Quattro, Xenon, Bose, Blinds, Solar Sunroof, TV, ACC, phone and almost every option. 168K miles rising slowly with retrofit AMI and DVB-T in place of Analogue 2003 Volvo S60 D5 SE Manual, 197K miles. 2001 D2 A8 3.7 QS, Bi-Xenon, Bose, Blinds, Electric Everything, retrofitted RNS-D, 191K Miles
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#4
1st September 2015, 08:28 PM
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Found one on ebay, looks complicated to replace it though as it appears to be located beneath the heater fan.
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Manny 2004 A4 1.8T Sport Cabriolet, 89K Miles Past 2004 D3 A8 3.7 Quattro, Xenon, Bose, Blinds, Solar Sunroof, TV, ACC, phone and almost every option. 168K miles rising slowly with retrofit AMI and DVB-T in place of Analogue 2003 Volvo S60 D5 SE Manual, 197K miles. 2001 D2 A8 3.7 QS, Bi-Xenon, Bose, Blinds, Electric Everything, retrofitted RNS-D, 191K Miles
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#5
5th September 2015, 02:29 PM
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Had a look at the location of the control unit, you can see it through the flaps after removing the cover and pollen filter. Looks reasonably easy to change, only headache is going to be the flap motor which I may have to remove to get the top off.
The flap motor is also jammed and has been since I got the car, so maybe a chance to replace that as well if I can find the part number.
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Manny 2004 A4 1.8T Sport Cabriolet, 89K Miles Past 2004 D3 A8 3.7 Quattro, Xenon, Bose, Blinds, Solar Sunroof, TV, ACC, phone and almost every option. 168K miles rising slowly with retrofit AMI and DVB-T in place of Analogue 2003 Volvo S60 D5 SE Manual, 197K miles. 2001 D2 A8 3.7 QS, Bi-Xenon, Bose, Blinds, Electric Everything, retrofitted RNS-D, 191K Miles
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#6
4th October 2015, 09:01 PM
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Mannyo,
When you do this, I guess you'll get pics and do a nice little post? be interesting to see. Good luck.
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[center] 06 3.0TDI Quattro: Options: Soft close Doors & Boot, Electric Blinds, Keyless Entry & Start, Bluetooth HandFree, Quad Zone Climate, APS+, 3 Spoke Sports Tiptronic Multi Function Steering Wheel, Heated Seats All Round, Black Leather Comfort Seats, AMI, Sunroof, Drivers & Passenger Electric Memory Seats, Auto Dimming Mirrors, Bi-Xenons AFS2, Dab, Digital TV, Reversing Camera, AV Inputs, Fridge, Solar Roof, TPMS, facelift rear lights, 3G, remote boot closure, Tow Bar.
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Hybrid Mode
