Rear Blower control unit for a MK1 Sharan

[Reelman]

Hi Guys,
I am totally confused, and even my local VW dealer looks at me as though I'm stupid. The auxilliary booster heater in the rear of my Sharan hasn't worked since I bought the car a few months ago, and with winter fast approaching, I need to get it sorted quick.

It is a MK1, which doesn't have a/c in the rear, just the hot air blower. A friendly autoelectrician did a VAG-COM test on the car and told me that the "rear blower control unit" had an internal error, and that because he was able to "force" the burner to ignite using the VAG-COM, the burner itself was ok.

However, I'm unable to locate this control unit. The auto electrician said it's usually mounted on the blower unit itself, behind the near side trim in the luggage compartment, but having removed the trim and blower unit, it's not there. He's now suggesting that on the MK1 version (without a/c in the rear) it was sometimes mounted on the underside of the vehicle near the burner unit itself, He seems certain that it's not housed in the burner itself and says that any electrics in here are just for the ignitor.

I do not know what to do now. I feel as though I'm almost home, but have lost my way at the end. Can any of you clever guys out there advise me as to where this control unity really is, before I strip even more of the car down in the hunt for it? Photos or a part number would be great too, if that's not asking too much ?

All advice gratefully received.

[the_old_diver]

Reelman, is there some confusion here? On my 1997 Sharan CL TDI I have an auxiliary heater which is meant to speed up the engine warming process by burning highly taxed road fuel. Mine is located somewhere under the left hand side rear passenger door and hasn't worked for years.

The vehicle also has an extra hot air blower for the rear seat passengers, the fan unit for which is located in the bump over the wheel arch again on the left hand side - the bump on the opposite side contains the jack, wheel wrench etc.

This rear fan unit is controlled by what I would call the "rear blower control unit" which is those two knobs above the rear left hand side door. See pic.

The diesel burning auxiliary heater heats all the water in the engine system, and the extra cabin heater matrix is supplied with hot water from the same single system.

[Reelman]

Thanks for that old-driver ~ you've explained that perfectly, and better than I could. However, there may be a little confusion here, as my auto electrian was initially referring to the faulty part as being a control "module", but later started referring to it as a faulty control unit.
He said he was aware that some companies claim to be able to repair "ECUs" but that he had his doubts as to whether these repairs would last more than a few weeks or months. He also told me the price of the control unit/module was about £137 plus VAT from VW, and recomended that I try to find a secondhad one.

I suspect it's not the rear fan speed control, as you've kindly suggested, as surely VW wouldn't ask that much for a simple thing like that, and nor could it be regarded as an ECU.
I have my suspicions that the ECU he is referring to is actually built into the Eberspacher itself, which might explain the costs etc, but my autoelectrician seems to think this unlikely. In his defence, he's not a mechanic, and has merely diagnosed the fault with his VAG-Com equipment.
Having now dropped from underneath the car, in order to look for a control module/unit tucked up behind it somewhere, which there wasn't, I can now confirm that it is a D3WZ Eberspacher ~ perhaps that will make it easier to identify this control module.

[the_old_diver]

Hi Reelman,
Glad you are making some progress. I would be very pleasantly surprised if VW would sell any of their "modules" so cheaply. There are two different bits that might be described as ECUs - the main one that controls the engine function and another called I think the Comfort Control Module which sits in a well under the front left hand seat - access from the back. This latter one controls door locks, windows etc and has a habit of drowning when the aptly named "well" fills up with water from a blocked engine compartment drain.

But before you go spending money please check with others if the auxiliary diesel powered heater is meant to work when the ambient temp is still around 10 degC - it may be that it is not working because the weather isn't cold enough, or because the glow plug is defective, or because a previous owner disconnected it on purpose. And don't forget to check fuses for anything that isn't working.

The engine glow plugs on mine don't heat in the summer / spring / autumn.

Check the forums here with the "Search" feature for past threads. You may need to experiment with various keywords to get the best results.

I'll check back later. OD

[Reelman]

I've been trawling the net, and managed to find this diagram of the D3WZ where it seems to suggest that part No.9 is a "control unit" ~ the last picture is the clearest.

http://www.matrasport.dk/Cars/Espace..._G9T_3426A.pdf

When I mentioned it to my auto-electrician, he said he thought that this part is simply the electrics for the ignitor, but admits he's no expert on these things.

Could it be the faulty part that his VAG-COM picked up on?
Anybody got a part number for it, or know the price?

As always, any info gratefully received.