The top four all project to the outside , the top two are hidden away under the "bonnet". The middle two are just behind the top of the radiator. As Covkid points out in the Wiki, these corrode and all the rust you leave on the end of the screw will have to be pulled through the captive bolt. So try to get hold of one of those little brass wire brushes the size of a toothbrush and really attack the ends of the screws. Then loads of Plus Gas or similar penetrating oil. Then get yourself a Phillips #3 screwdriver at least 200mm long and with a square shaft if you can get it. (For extra leverage with a spanner or molegrips) I made the mistake of getting a 150mm Pozi 3. (USE PHILLIPS !)So if you are lucky you can get the right hand top two off without shearing one off like I did. Then I tried the other side, next to the steering column. Awkward isn't the word, especially if your screwdrivers not quite long enough.... you need lots of leverage too, and I just dropped the steering wheel onto the seat, all plugged in and wheel on. So its a "bar-steward" at the best of times, make sure you are well armed and prepared, maybe preparatory plus gassing would be an idea too.
So yes you guessed it I stripped the head on the last one, the lower of the two which you have to remove the dog legged bit of fat vent pipe to get to. It is right behind the master cylinder. So I ended up chopping off the corner mount (It was getting late by now).
So at last I got the heater off, left the coolant pipes still connected, cables still connected. You can now put your hands in the front fresh air vent to get to the motor. Mine was seized solid as suspected (drew amps off the battery when switched on but no noise whatsoever) but got it spinnning with loads of plus gas and spinning by hand till I felt it start to spin a bit more freely. It never seemed to spin very freely though.
Anyway that is that, reassembly was easy, (I am now short of two out of six mounting screws but have two each side) and hallelujah the heater works. Reeks of plus gas, but quiet as a mouse !
I bought shear bolts in advance but should have checked first, they had already been replaced by normal bolts. I guess what you could do to be safe would be to buy a heater motor from GSF (£50) but don't unpack it
and if yours is FUBAR'd you have it to hand to replace. And you will need the clips too to attach the box back together, but it seems they are on the very endangered list at VAG... But like CovKid says, 9 times out of 10 the motor will just have seized solid due a bit of corrosion and not being used.[/b]
As Ringo said, which vent is this?