

| Subject: | Re: Hanging flaps in heater box |
| From: | M Kaz |
| Date: | Thu, 5 Oct 2000 09:46:16 -0400 |
Hi All, I am right now working on my heater box and was wondering if anyone knows where I can get replacment brushes for the blower fan? I figure since I'm in there I might as well do it now while its out. Also has anyone replaced any of the foam flap seals? mine are shot, and I was wondering what others have used . TIA Mark K. > ------------------------------ > > Date: Wed, 4 Oct 2000 15:44:30 -0400 > From: David Beierl <dbeierl@ATTGLOBAL.NET> > Subject: Hanging flaps in heater box > > Ok, I understand what the free-swinging flaps do in the heater box. They > matter... > > Heater box has three functional parts: cold air inlet, cold air plenum, hot > air plenum, arranged top to bottom. The blower is the obvious connection > between the inlet and cold plenum, but VW added two big holes (about 3x6" > each) so that ram air wouldn't have to pass through the blower to get into > the plenum. But now of course the blower output is short-circuited right > back to the input; so they added a couple of very light swinging flaps that > close off the holes whenever the pressure is higher in the plenum than in > the inlet. The design (if you can call it that) of the flaps is such that > they ordinarily fail open, either by sticking or by falling off. Either > way, result is that you get greatly reduced blower output. > > The flap design is bad because they made the wearing parts out of plastic, > and doubly so because the pins on the flaps hang from the open ends of the > little clips they're stuck into instead of from a solid part. So as the > pin gets smaller, the opening also gets wider until the flap falls off. > > Fixes -- 1) new middle section (that's where the hinges are) and new flaps; > 2) build up the pin thickness with epoxy -- it's unlikely to have broken > off completely -- and make new hinges. This is hard because there is no > access. I succeeded by heating brads and driving them through to support > the pins, but it's still hard; and you have to remember to put the flap in > before the second hinge since it no longer snaps into place; 3) in a pinch, > close off the holes permanently. This will reduce the flow of ram air > because it will have to pass through the blower, but it's better than nothing. > > These flaps are covered with light foam (easier than putting a narrow strip > on the edges) but I see no need to renew this as it mostly reduces the > noise of the flap hitting the frame. As long as there aren't lumps > standing up in some places and not others, there should be no functional > difference. > > david > ps -- we might consider a contest for how far someone can send one of the > spring clips that hold the box together -- and still recover it. They're > snappy little guys, pays to hold your finger over them whilst > removing. Did I hear they're close to $4 each at the dealer? > > pps -- I would strongly recommend replacing the M6 screws holding the > heater box to the vehicle with M6 bolts instead, and generously anti-seized > at at that. This is an area that takes a hit when the windshield leaks, > and the ends of the upper four screws/bolts are out in the open > anyway. Might similarly replace the Phillips screws on top of the dash > with hex-head screws as they are quite difficult to drill out with the > windshield in place. > David Beierl - dbeierl@attglobal.net <<- New address becomes mandatory on 1 > Oct, optional until then. > > ------------------------------
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