Background

See also Jaguar XJ6 airflow discussion in the Climate control options post.

Fresh air pull knob

Midway through the Series 1 XJ6 production in the early 1970s, Jaguar introduced a fresh air intake routed through the front headlamp embellishers. A tube passed along the front wings, made a sharp turn, and then entered the side of each foot box. A flimsy pull knob operated a circular blocking plate inside a vent housing.

By 1981, this rather curious venting system was discontinued on climate-controlled cars by blanking off the footwell panel access hole. Jaguar XJs before 1981 as well as and post-1981 cars with a heater unit only (that is, no air conditioning), maintained this intake as a source of fresh air.

Flimsy fresh air vent pull mechanism operates circular blocking plate

Circular air blocking plate inside housing

Fully open vent still blocks fresh air

The convoluted airflow through the headlamp embellisher made this system inefficient to begin with — little air actually enters the cabin — but the problem was exacerbated by the awkward circular blocking plate. Even when pulled open, the air passage was partially blocked by the circular plate!

Still, Jaguar engineers apparently believed this unsophisticated opening worthwhile … it remained in production for nearly two decades!

The vintage Jaguar air conditioning system pulled in fresh air through the center hood vent and thus made the side foot box vents redundant.

Our Vintage Air HVAC unit only recirculates air, and therefore some method of fresh air intake makes sense.

Modified design

Modified vent housing

Fresh air intake efficiency can be improved by removing the circular blocking plate assembly entirely. If left completely open, there would be now way of closing off the fresh air supply, so a new kind of louver is required.

Since the depth of the housing is small — only 1 to 2 inches — no commercial louver will fit. The 2.25″ diameter hole is also non-standard.

3D printed louver

Custom 3D printed louver fits into vent housing

A custom 3D printed louver fits in the limited space. When opened by hand (the pull lever has been eliminated), airflow isn’t blocked at all. Admittedly, it’s a little uncomfortable to reach down to the side of the foot box (especially difficult on the driver side), but opening and closing the vent isn’t likely to be a frequent task. Only in very cold or hot weather would fresh air be closed off.

Back view of the custom louver in the closed position

The 3D printed vent housing and louver pieces were assembled with small metal pins and glued to the original metal mount with JB Weld. The simplified operation is very efficient (nearly all the air is blocked when closed and unblocked when open) compared to the earlier OEM design.

Open and closed louver on side fresh air vents