Original Text by Jerry Skene,
Additional information from Jimmy Shrake, firstname.lastname@example.org and Ron Stygar, RonStygar@aol.com
Changing the micro filter is not a difficult task and should take about 45 minutes. The filter is mounted vertically, on the front of the center console, right below the center of the bottom of the windshield. Just follow the instructions below.
Apparently there are three styles of glove boxes on the E36 cars. On some models you may not have to remove the kick panel. It also may not be possible (or necessary) to remove the two air vents and screws behind. On 1995 and newer models there is a 10 mm bolt behind the glove box light.
If you can't get the electrical distribution block out according the instructions, remove the three 8mm bolts holding the assembly and move the whole assembly out of the way.
Remove Passenger Kick Panel:
To remove the passenger kick panel, remove the two Phillips head screws at the left and right corners of the rear edge of the panel (the edge closest to the rear of the car), just below the bottom of the glove box door. Now slide the panel towards the rear of the car (towards you), out of its retaining clip on the firewall. This is easier to do if you first push the air vent protruding through this panel up so it clears the panel, and bend the curved left side of the panel away from the right front edge of the center console cover, so it won't catch as you pull the panel out.
To remove the glove box, flip the left and right air vents above the glove box down, then pry them out with your fingers. Remove the black Phillips head screws now visible in the air vent holes. Open the glove box door and using a small slot screwdriver, pry out the two D shaped screw covers at the top left and right of the glove box opening. Remove the two black Phillips screws behind these covers. These two screws have a small ridge to retain the D shaped cover and must go back in the original locations. Using an offset screwdriver or short Phillips bit in a 1/4 socket, remove the two screws at the lower left and right of the glove box opening. On 1995 and newer models remove the glove box light and remove the 10 mm bolt behind the light. Pull out the glove box and put it on the floor. You do not need to remove any wires from the rear of the glove box.
To get clearance for the filter, you must move the electrical distribution block behind the glove box out of the way. This block is in the upper left area behind the glove box. It has a large bundle of wires coming in the top, and an orange relay mounted on the left side. This block can be slid up and out of its retaining slides if you first release the catch that holds it in place. The catch is on the right side of the block, about half the way back. Slide a slot screwdriver between the right side of the distribution block and the left side of the plastic electronic module holder, and push the top of the catch in (towards the left side of the car). While holding the catch in, slide the distribution block up and out of its retaining slides. Move it down, away from its normal position.
Move the Passenger Air Vent Pipes:
Now you must move the passenger air vent out of the way. To do this, use a flat screwdriver and pry the duct-retaining pin out of its hole. This pin is located just to the rear of the front lower, cadmium-plated Torx screw on the HVAC box, at the front of the console. When this pin has been removed, bend the vent pipe down.
The filter cover is hard to find. Just in front of the above mentioned Torx screw on the HVAC box is a cylindrical 1 1/2" diameter handle, with 2 rectangular protrusions molded into it. Turn this 1/4 turn counter-clockwise, and pull out the filter cover attached to this handle. Feel inside the opening created for the tab handle on the filter itself. This is slightly above where the round handle was. Push this tab towards the front of the car and then pull it out to the right. You will have to push the vent pipe down, out of the way with your left hand to get enough clearance to remove the filter. If the filter is the original one, the frame will be in one piece and will have to be snapped in two places to allow the filter to bend towards you, so that it will clear a bracket mounted to the car after the filter was installed at the factory. Examine your new filter to see how this works. The plastic frame has two slots and clearance wedges molded into it on the top and bottom edges. With a little force you can snap the frame at these slots, so that the filter now bends in two places. Do this to the old filter, and you can then remove it easily.
Install New Filter:
Snap the new filter's frame as described above, and slide it into the filter slot. The filter should be oriented so that the handle is close to the top right corner of the frame. Once the filter is fully inserted, pull the tab towards the rear of the car, seating the filter in place. Replace the filter cover, ensuring that the wide edge of the cover plate is facing the rear of the car. If you have difficulty replacing the filter cover you might not have the filter seated fully. You can use your fingers to push the right edge of the filter forward. The gap between the front of the filter and the finter housing should be the same at the top and the bottom. Move the passenger air vent back into position and replace the plastic pin. Slide the electrical distribution block back into place, so that the locking catch snaps back into place. Replace the glove box, vent grills, and kick panel