Date: Thu, 30 Jul 1998 20:09:17 -0400
From: "Brant M. Miller" <brant_at_compuserve.com>
Subject: <E34> Microfilter
Peter, the Bentley Manual and other sources say the microfilter started in
1992, so you should have one.
Re instructions for changing same, there has been much on the Digest over
the years and the Bentley Manual can also help. I've reproduced my hash of
good advice originally provided by Kurt Gibble and Dan Quicker below - my
appologies to the two of them for any deteriorations I may have introduced.
Kurt had (has??) the instructions on a web site, however, I've lost the URL.
When you are all done, you will have a new appreciation for how footprints
get onto BMW headliners!
Kurt Gibble (9/91 E34 M50 5sp) provided most of the below information with
comments by Dan Quicker ('95 540ia) incorporated. I've added a bit to
reflect my experience with the microfilter on my 1995 525i.
Working somewhat from Chilton (just short of useless for this job) and mostly
from BMW fiche:
- Remove glove box by removing the retainers holding the strap and gas strut
(if present) from the sides of the glove box. Lying on the floor, loosen and
release the latches for the rear hinges. Dan says "Glove box is now sitting on
your head." Just reach under the glove box and pull the snap connector
releases down. The connectors will then slip off the mounting rod.
- Remove the carpeted panel on left side of pass. footwell. On Dan's 540, the
carpeted panel was screwed to a gray mount that is removed by pinching the
mount and sliding it out. This mount would have been in the way when you
slide the filter out in step 6.
- Remove the black cover on left side of glove box. (On this, the fiche has the
wrong picture in Sec. 64-31/2 but I believe Fig. 2 of Sec. 64-31/1 is correct.)
Remove the small duct going to the RHS of pass. footwell. On the 540, the
black cover and the RHS footwell duct should be removed as one piece. On
the '95 540 there are 4 screws and this sounds like what I remember for my
a)1 holds the top of the black cover to the dash.
b)2 secure the duct behind the glove box hinge mounting bracket. On the
'92, these easily fall down in between the bracket parts - it's hard to
retrieve them from there!
c) 1 well hidden screw holds the duct directly above the 90 degree bend it
makes from the console to the footwell. It is on the top side of the
duct. (On my 95, the fourth screw connects the pannel to the top of the
glove box compartment.)
Turn the assembly out of the way. (The wires to the flashlight don't have
to be removed.)
4) On the '92 (and my 95 525i), remove the wires for the HVAC control unit (I believe that's
what it is) at very front & bottom of the console, right next to the fire wall.
Wires have a v nice, arguably over-engineered, connector - lift the lever up
and the plug automatically comes out. On my 95, the lever does NOT lift
up!! Reach behind the lever and press the catch in. Then rotate the lever
back. A cam will disconnect the electrical connector.
Release the clip and pull out the control unit. Dan says that on the '95 540, you
can leave the wires attached and just set the unit aside - pick your poison.
NOTE: Over the AC coil and heater core, there is a black cover with 7 T15
screws. The microfilter's not under there! You don't have to remove it -
beender dunyat (see step 3 about wrong fiche picture.)
5) Down further & recessed (toward the center line of the car) is a small funny
shaped (tall and thin) white cover (on mine) with 1 or 2 screws (T15 I believe).
The microfilter is under there. I think you get it loose and then have to rotate a
lever to get it out.
On the '95 540 (and on my 1995 525i), Dan says the white cover is right
next to the control unit. It is
held with 1 T15 screw and a cam lock lever at the top. Loosen the screw, Turn
the camlock counterclockwise. Remove the White cover. The filter is right
behind it. As you can imagine, the white cover is as tall as the filter (5"?) and
about 1 1/2" wide.
6) Pull the filter out. While your there, clean out any junk in there that you
don't want to blow out of the center vent and into your face. (Leave the junk
that you do want blown into your face.) (Be careful not to damage the air
conditioning radiator while cleaning the coils. It is easy to mash the
7) Trivial Step: Assembly is reverse.
Took me ~2 hours first time because of the brevity of Chilton and the error in
BMW fiche. Should be a 30-45 min job 2nd time. (Took me about 4 hours first
time. Much of which was spent on the electrical connectors.)
From: Peter B <pb_at_xyz.com>
Subject: <E34> 1992 525i, Microfilter question
The car in question is a manual 1992 E34 525i with the M50 engine. (7/91
Does anyone know if this car has a microfilter like the E36's that needs
to be replaced periodically? The A/C intensity has dropped off somewhat
(though he it never really was that strong to begin with) and I was
thinking maybe the problem is with a dirty microfilter if there is one?
If there is one is it as easy to replace as on the E36's? Thanks.
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