Flaps in the 'blender box' for the heater are perforated with large holes and nominally covered with sheets of foam. Over time, the foam degrades. Pieces of foam will start flying out of the dashboard heater vents and windshield defrost vents. Large pieces may clog the ducts. One flap controls the direction of flow through the system (whether heat or AC should be directed to the feat, or the dash vents). Another flap controls the temperature by regulating the flow of air across the heater core. When the foam is lost and the holes are open, control of the system is lost.

There are at least four approaches to restoring control by closing the holes in the flaps:

Remove the center console and reach into the intake for cabin air recirculation and place tape over the holes.
Cut into the side of the blender box and place tape over the holes.
Separate the blender box and drop it down and out so that the flaps can be worked on.
Remove the entire dashboard, which makes the entire heater assembly accessible.

Case Studies

Recirculation intake

In this particular 1997 EVC, the foam was gone on the direction flap, but still intact on the temperature flap.

In this case, foil HVAC tape was applied over the holes by simply reaching into the recirculation port. Alignment was not exactly perfect. This unit will probably need to be revisited when the temperature flap foam goes.

This approach in fact does not cover the whole directional flap. This flap has a crease in it that actually creates two separate flaps that rotate on the same axis. The other part of this flap is not accessible from the recirculation port.

Cutting the box

A Rialta owner has created a writeup on a technique that cuts into the blender box here.

Splitting the box

Forum correspondent rdwalker owns a 1992 Eurovan and posted to this thread in a Bentley technical forum describing how he was able to replace his heater core without removing the dash. Another owner of a 1999 EVC claims to have used these instructions to replace his foam. These messages can be found here and here . Those links will require authentication to the Yahoo ev_update group.

Removing the dash

One such process is documented in a write-up here . It refers to a series of videos that start here .

Heater Flaps

Contents

Case Studies

Recirculation intake

Cutting the box

Splitting the box

Removing the dash

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