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Friday, February 22, 2019

Doug's Domain

Doug Vetter, ATP/CFI

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BMW E36
Center Vent Replacement DIY

(Image: Center Vent)
Cost of a new center vent to replace the failed part: $55.
The ability to control where the fresh air goes on a hot day: Priceless.

Introduction

For the last several years, the center vent (above the radio) has not worked properly. Whenever I tried to use the control to redirect the airflow it would bind. Since this vent provides the greatest airflow of all the vents in the dashboard, its failure was a real inconvenience. This DIY explores the relatively simple process necessary to replace it.

Prerequisites

Replacement of the center air vent requires the following:

Procedure

Removing the old vent

  1. Take a look around. Before we get started, first things first. Take a good look at the driver's side footwell ceiling panel. It consists of a black portion under the dash near the driver's feet and an interior colored panel that slopes upward to a point just under the steering column. Unlike the passenger side, the lower panel is joined to the sloped portion and cannot be separated. Take note of how the edge of the horizontal portion of the panel mounts under the dash in the vicinity of the pedals. The front left corner slides into a plastic slot molded into the kick panel and a tab near the center fits around a rubber o-ring type of isolation mount. Since the panel is rigid, you must make sure that the front edge is properly positioned when reinstalling the panel. It's difficult to describe, hence my recommendation to look at it closely before you pull it apart.
  2. Remove the driver's side footwell ceiling panel. Start by removing the three (3) philips screws that affix the panel to the dashboard. Two of the screws face aft and are located at the dividing line between the interior colored panel and the center portion of the dashboard which is black in all cars. The remaining screw faces down and is near the center console. You must stick your head in the footwell and look up to see that screw. Note that all three screws are different types and lengths, so be sure to make a note of which screw goes where. When the screws are removed, grab the panel and pull it straight back. You should note that a retaining clip built into the panel sticks into the side of the dash so you may need to pull the top left of the panel to the left (towards the door) as you pull the panel aft to get it to release. As you pull it aft, be careful that you do not stretch the electrical leads going to the footwell light or the chime speaker. In fact, once you have moved the panel far enough aft, you'll need to reach in and disconnect those connectors before you remove the panel from the car.
  3. Remove the driver's knee protection system. This consists of a metal assembly filled with foam designed to protect the driver's legs in a collision. The is fastened to the car's steering column supports with three (3) 10mm bolts. The bolts are recessed into the panel so you'll need a deep socket and a ratchet at a minimum to remove them. I used a 6" extension and a shallow socket and made easy work of it. As you lower the panel down, you may note that there is an electrical connector fastened to the front left edge of this assembly. You do not need to remove that connector as it's possible to position the panel vertically, parallel to the kick panel and keep it out of the way of the work at hand.
  4. Remove the footwell ductwork. This is a black plastic duct that connects to the HVAC plenum in the center of the dashboard (behind the radio, OBC, etc.). It snaps into the HVAC plenum and is also held up with a black plastic rivet. It's easiest to disconnect the duct from the plenum first and then wedge a small flat-blade screwdriver under the mounting tab through which the rivet is fastened to release the assembly.
  5. Remove the radio. There are small plastic "doors" on the far left and right side of the radio face. Pry those open using a small flat-blade screwdriver and then use the special 5-sided allen wrench to unscrew both retaining screws. They will only unscrew so far. Do not attempt to unscrew them beyond that point. Once both screws are fully loosened, stick your finger in the cassette door and pull the radio out. WARNING: If you have been playing the radio at any time in the last several hours, the radio case may be scorching hot. I found I could not hold the radio bare handed for more than 3-4 seconds without pain. In retrospect, some cloth gloves may have helped here, but I didn't have any handy. Once the radio is removed, you'll note a large connector and a few other wires connected to the rear of the unit. It is NOT necessary to remove any of those wires except perhaps the large black antenna cable (far right side of the rear panel of the radio) because that can be stretched a bit too much. I removed that antenna lead just to be on the safe side, but otherwise left the radio attached to the car, with the unit hanging down vertically. That saved me from having to enter the security code to reactivate the radio or reprogram my presets.
  6. Remove the center vent. Begin by using a right-angled screwdriver to remove the two screws on the bottom of the vent, now accessible through the radio mounting hole in the center stack. After both screws are removed, wedge your fingers into the vent and pull it aft slightly. The bottom should release easily but the top left of the vent may get hung up slightly as the clip hangs on to the dash. Do not force it. As the bottom edge of the vent clears the dash, simply pull it downward and to the right to free the clip. It's easier done than said...just be aware that you can't pull the top left of the vent directly aft or you may cause damage to the vent, the dashboard, or both. Note that at this point the vent will NOT come out of the dash more than about an inch because the diverter cable is still attached. That's fine. Just leave it there for now.
  7. Detach the diverter cable assembly from the air control flow arm. While most of the plastic behind the dash is black, including the ductwork, BMW had the remarkable foresight to sleeve the control cable in bright blue PVC, retain the cable using a bright yellow clip, and terminate the end of the cable in a white fitting resembling a banjo. All are perfectly visible under the dash if you look for them. A flashlight is helpful in any case. The clip detaches from its mount by pushing the clip upward as it will slide out of a slot in the HVAC plenum. Then, detaching the cable from the control arm is as simple as lightly tugging on the cable with one's thumb and finger. Again, easier done than said.
  8. Remove the vent from the dashboard, taking note of how the cable is routed into the dash and being careful to make sure that the cable is pulled up out of the dash without binding on anything.

Installing the new vent

This is essentially the reverse of the installation procedure. I would recommend you turn the temperature control on the vent to the cold position so as to extend the cable fully. That will make it a bit easier to grab onto it under the dash and reinstall the cable end on the control arm. When inserting the vent in the dash, be careful routing the control cable down through the small hole to the left of the radio tray and be sure the vent fits inside the ductwork at the rear of the bay before pushing it home.

Highlights

Conclusion

This was a very simple fix. It took me about 20 minutes of actual work and about 10 minutes to grab my tools and clean up afterward. I don't have book labor on this task handy, but I cannot believe it's less than an hour. For that reason, I'll say that this saved me an hour's labor, or about $110. I also saved about $20 on the vent by purchasing it from Tischer.