I had some quality time in the garage today. First things first - I was able to get the heater core out. It looks awful. I think I need to call the Ghost Busters.



Much like Cortez burning his ships, cutting the right hand support meant there's little chance of me turning back. The good news is that the Vintage Air unit easily fits and there's plenty of room to rebuild the support.


I'll have to re-work the mount that comes with the Gen IV box but that should be easy enough.


I learned that one of the control boxes for the GenIV unit lets you remove the dials from their box and use it in your own. So I'll be able to use the left factory knob position to control the temperature and the right knob to control fan speed. I'll need to come up with a place to mount the knob for heat/vent/defrost but that should be easy enough.

Next up - adapting the stock defrost/front vent panel to be a defroster only. Then I need to figure out the factory fan boxes I want to make the driver's side an on-demand fresh air vent. The passenger side I'm hoping to connect to the GenIV box.

 

Thorsen
This is a really interesting and worthwhile project for many of us, I am sure. Parts for the OE system are non existent, and driving an XJS in summer with no aircon is impossible. A detailed write up like this will be really valuable on the forum.
Does the new system have its fans incorporated inside the unit, so can you do away wit the OEM fans?

 

Thorsen,

Do you know if their units are handed? From a very quick look at your photos, it seems it's practical to mount that unit in a LHD car but looks as if it might foul things in a RHD car?

Great project!

Paul

 

@Greg in France the new unit has it's own blower motor. I've removed the two Jaguar fans from the firewall.

 

@ptjs1 the units are not handed from what I can tell, but in thinking about your question it made me realize that it would probably fit better in a LHD car because you could put what I consider the bulky part of the unit (blower fans + evap and heat core) in the center part of the dash.

So I went out to the garage and turned the unit around. I'm not sure if the real unit would work this way, but it would simplify hooking up the heater hoses and refrigerant lines. I'm thinking it would also preserve some glovebox room.
The downside is that it would be almost impossible to hook up the new blower motor to consume outside air.
Which ever way I end up mounting it, there are mounting points on either side so I have that going for me.

 

THorsen
Could you please post a phot of what that RHS strengthener looks like now it has been modified, so I can see how much has to be cut away?
And second, could you please measure what the exact distance is betweenthe two strengtheners?
Thanks
Greg

 

I show the uprights are 17-15/16" inches apart. As they are perfectly vertical it is the same at the top near the windshield and the bottom near the transmission tunnel.

Here's what it looks like now as well as the piece I removed.

 

Thorsen,

So, just another thought:

Rather than turn it around, in a RHD car, would one just cut the LH strengthener and move it across to the left? Also, do you think there's room to fit it of one has a passenger airbag (either LHD or RHD)?

Tks

Paul

 

Yes, in a RHD I would cut the LH support. The vent outlets would be close to the left side of the car but I don't think that's a deal breaker.

Not sure about air-bags. In my experience with other cars those are usually mounted to a steel structure behind the dash and I don't know what the XJS looks like.

 

I spent some more time on the Vintage Air site last night looking at the Gen II Super unit - and started wondering if it might be a better fit. I called up Vintage Air and spoke to one of the Techs who walked me through both units. At the end of the day it sounds like if the Gen IV fits then I should use it, but he did acknowledge it's a bigger case than the Gen II.

So I have a Gen II mock up unit coming this week and by next weekend I should be in a position to pull the trigger on something. Which is good because I still have to do the transmission swap and rebuild the rear end.

 

The FedEx truck brought me a Gen II Super mock up unit today. I'm liking the way this looks but I am concerned about the distance to the defrost vents (it looks to be really close) and the wiper motor plug on the firewall means the unit would have a slight angle. I need to see how things looks with the dash in place before I make my final decision.

 

51,000 miles very nice black.

 

After putting the dashboard in place, it became apparent that there was just not enough room for the Gen IV unit but the Gen II Super unit had room to spare. So my Gen II Super arrived today.

The part that I did not realize is that it looks like 4 screws hold the blower assembly to the box. If my guess is correct, I can easily remove the blower, mount the case in the center of the dash, put the blower closer to the passenger side footwell, and run a duct between them. Not unlike the factory setup. Which also means I can weld in the bracket I chopped out.

Next step - voiding the warranty.

It does make me wonder if the Gen IV would fit if I pull the blower off the case...

 

A total of 7 screws and I was able to separate the blower fan from the HVAC box.


With the fan off, the HVAC box easily fits in the center section.


It's hard to get good pictures, but there is around 6 extra inches between the unit and the backside of the dash.



Here's the Vintage Air blower fan running at full speed.

Here's the factory fan running at full speed.

I don't have a way to objectively measure airflow, but it feels like the Vintage Air fan moves slightly more air. But it would be less than two factory fans.

 

Separating the fan from the body of the unit is a great fix, Thorsen. I take it that the fan just recirculates cabin air? If so, you could, I suppose, also duct fresh air to it if you wanted to, or even have a flap to choose?

What id the difference between the G II and the G IV, please?
Also where on the unit are the pipes to connect to the water and aircon? Are they reasonably easy to hook up to where the OEM pipes come through the firewall?

 

The fan just recirculates cabin air but I'm working on a plan to mount it where the passenger side fan was and have the option of fresh air vs cabin air. More to come on that.

The Gen IV has a variable speed blower fan, the Gen II only has 3 speeds.
The Gen IV uses an electric thermometer to measure evap core temperature, the Gen II uses a mechanical thermostat probe.
I believe they both have stepper motor control of the diverter flaps.
The Gen IV uses a 3 knob control panel (temp, fan speed, air position) while the Gen II uses 4 knobs (cold temp for the AC, hot temp for the water valve, fan speed, air position)

The coolant and AC pipes will be easy to work with. They both face the passenger side but it will not be difficult to make them reach the factory location. I'll use a bulkhead pass to safely pass through the firewall.

 

I spent some time in the garage today working on the new HVAC box. The first order of business was removing the excess parts from the defroster assembly. I removed the front vent/defroster vacuum motors and got out the angle grinder.


The Vintage Air kit comes with defroster ducts, which meant I needed to remove the stock defroster flap.


It was easy enough to attach the Vintage Air defroster assemblies to the defroster panel.


Next up was securing the HVAC box in the dash. I used some 1/8" steel to make a bracket for the left side of the unit. Here I am lining it up.


And here it is after welding the tab on.


I modified the factory mounting rods that go from the side of the transmission tunnel to the face of the factory unit. I cut off the old tab and welded on a steel extension.


In this picture you can see the mount I fabricated for the left side and the modified factory mount.


Here is the right side of the unit. I'm not done here yet - I will make a side mount once I get the support panel back in.


Here is a view looking straight ahead. You can see I have the defroster ducts hooked up to see how much room I have.


The next steps are:
- convert the fresh air/recirculate boxes from vacuum to electric operation
- mount the blower fan on the right hand side box
- plumb the blower fan to the heater box
- modify and weld in the support I cut out

 

Came home from dinner and there was a package waiting on the doorstep for me. I ordered some to control the fresh-air/recirc door. I removed the vacuum motor and mounted the actuator to pull on the top door.


Apply +12 volts to the red wire and ground the black wire and the actuator extends. Reverse the polarity and it retracts. I have some switches to control it on the way but for now I just flip the wires.

 

That I really like!

 

Today was a short day in the garage, but I was able to mount the blower fan to the fresh/recirc air box. Nothing fancy; just a thick layer of weather-stripping between the two and a couple simple steel brackets (only one which you can see in the picture) to hold them together. Once I'm happy with all my brackets I'll throw them in the sand-blaster and powder coat them.

I'm using 4" duct hose that I picked up from the hardware store. I'm not a fan of the look and 3.75" hose would probably fit better, but ... $11 for 25' of the cheap 4" hose versus $20 per foot of 3.75" black hose. I think I can use some duct tape on the ends and be OK with how it looks safely hidden from view underneath the dash.