Here it is - the project that started me down the path that had the most scope-creep, or “While I’m At It” syndrome of any project ever - Jeep, house or otherwise.

It started simple enough.  SSDutch came from Texas, and had no heater.  I wanted a heater.  So I bought a heater - a two-duct version of this Heatercraft unit.  I found one on eBay that had been purchased and never installed—so saved a few bucks.  It came with the heater, ducts, vents to mount in the dash, a switch, and some misc. connectors and fittings.

But - I wanted to run one of the ducts to a defroster tube to help clear the windshield, and SSDutch came with gauges mounted where the duct has to run.  While pulling down the dash in order to redesign it I decided that it would be a good time to completely strip and repaint the interior.  Then it also seemed like a good time to completely rewire the entire Jeep.

Add in some house projects, other Jeep-related projects, and life in general and it ended up that the heater installation has taken the Jeep off the road for over two years.

As of this writing I’m still working on getting the Jeep back together, but the heater installation is now complete so I can put together a project page for it.

Heater Unit
I started by finding a place to mount the heater unit on the firewall when the dash was off.  There isn’t a ton of room to work with, but the unit does seem to fit the space nicely.  There is a small piece of channel on the firewall right behind the heater (originally a support for the oil-bath air cleaner), but the brackets allow the unit to be spaced out from the firewall by 1/2” or so.

I’ll need to move it back towards the firewall by 1/4” so I can fit a duct hose on the defroster duct:

Unit will be visible under the dash.  The 4” hole will be where a dash-vent is placed.  Looks to be enough room for the switch panel that will mount over the rectangular hole.  There is plenty of clearance between the heater and the glovebox.

The project then went on hold while the entire interior was stripped and repainted (insert spinning clock here).  Once that was done I started by making a small modification to the defroster tube:

These aftermarket ones are basically two pieces of plastic with a seam that’s supposed to be plastic-welded together.  This one was split already, and overall it just looked designed to collapse when you tightened down the vent hose. 

I found a PCV elbow that matched the inner diameter of the defrost tube, so cut it off and screwed inside the end for support.  I also put a series of screws down the seam then sealed it up with some silicone.  Looks like an old ladies boot, doesn’t it? 

Then re-installed the heater and defroster tube:

Heater Hose Routing
I routed heater hoses through the firewall on the passenger side - below the glovebox.  On the engine side this puts them just underneath the battery tray. The left hole was there already with a cover screwed over it, the right hole I had to make.  The hose boots were grabbed off a junkyard Toyota 4Runner.

Switch and Vents
I used the switch that came with the heater:

I mounted it to the left of the driver.  This isn’t my first choice for a location - I’d rather have it in the middle where the passenger could control it (my wife being more temperature sensitive than I am), but as the dash worked out this was the best location.

The vents that came with the heater rotate in addition to having the flaps that open and close.  This will allow pretty nice control over airflow - I can force it all to the windshield or more to the passenger side by changing my vent:

I mounted the vents as far outboard on the dash as possible - you can see them in this picture:

Ducts
I have two outputs on the heater - one goes directly to the defrost tube for the windshield.  The other is runs to a “T” located above the steering wheel, then from there to the driver’s side and passenger side dash vents.

Here’s the heater.  The left output is obscured but does run to the defrost tube - visible top right.  It runs up right behind the switch panel mounted on the dash.  There is room - but it’s tight.  I wrapped the duct in two layers of milk jug plastic, then duct tape in an effort to prevent the wiring from poking holes through the duct.

The visible right heater output is running to above the steering wheel where the “T” is secured.  The left-most duct runs to the passenger side dash vent.  I’ll have to tidy this up a bit yet as I expect some interference with the gas pedal that isn’t yet installed.

The angle on this picture is tough - you’re looking up towards the cowl right next to the steering column - you can see the support for the hood hinge in the background.  This is the “T” that splits one heater output to two dash vents.  It’s held in place by wire ties that are attached to anchors with adhesive strips on them - stuck to the underside of the cowl.  I located this here simply because there was room to get it out of sight.

Driver’s side dash vent - the other end runs to the “T”.

Passenger side - this runs between the heater and glove box, over the heater hoses.  It’s a bit of a tight fit but seems to work OK:

Summary
I have yet to field test the heater - but have had the Jeep running long enough to know that it works. The volume of air out the dash vents is pretty good.  The only thing I may add in the future is an inline water valve - both to adjust the temp of the air and to be able to shut off the heater in the summer.  Those heater hoses get pretty warm and they are a bit close to the passenger’s feet.