Rethinking Coupe HVAC

[Chris @ Forma]

As some of you may know, we go a bit overboard on our interior and creature comforts, meaning among other things, HVAC. We've built a couple of coupe systems adapting units from Restomod and Vintage Air. Frankly they left me underwhelmed and disappointed in our results. As we have another coupe in process. I decided to take a clean sheet of paper approach. I started with the following requirements:

Has to work with our interior/dash
can't preclude a glove box
has to provide blending between floor, dash, and defrost
needs production car cooling and heating performance
need to be able to install in an in process car without removing the body


The attached images show the design. I've built one on the bench and the performance is better than I expected. I'll be installing in the next week or so. I'm unfortunately trying to finalize our window details in the short term. Anyway a couple of key features:

much of the unit resides behind the engine and just in front of the firewall
The blower motor resides at the extreme forward upper passenger footwell drawing all the air from inside.
Pretty much all of the parts are printed in nylon 12
rather than damper doors, the air valving is handled by a cylindrical coaxial valve sleeve that rotates inside the cylindrical manifold
valve actuation is handled by stepper gear motor
controls us a PIC micro-controller
Temperature sensing is handled via thermisters


Anyway, it is a bit over the top. Guys at FFR confirmed my insanity but I think it is going to work great and it looks like our cost will less than buying someone else's and adapting it. One of my builder friend asked if were going to sell this as a kit and that is a definite maybe. Please throw stones, critique, tell me what you think. 132756132757132758132759132760

[John Dol]

Chris,

I think that's dope! Will the squirrel cage be insulated? Wonder if the header heat will impact it?
Think if its cheaper then the factory set up then it will be a hot seller.

John

[FFRWRX]

I was wondering the same thing, will the engine heat be an issue? And what was the issue with the Vintage Air stuff?

[Chris @ Forma]

A bit of clarification. The blower motor resides inside and at the extreme top/forward corner of the passenger foot box. All the air is drawn from the passenger compartment, passes through a combination heater/evaporator core and exits the core box at the rear of the engine compartment. The cylindrical valve duct assembly receives the air out of the top of the core box and conveys it to the center line of the car where the valve assembly distributes the air to the foot boxes, dash, and defrost or any combination of two. As for the material taking the heat, it is the same plastic used for OEM intake manifolds so we should be fine. The problem that we have experienced with vintage air is that their larger units just didn't fit and their smaller units didn't have enough cooling power. Furthermore they took so much space that they precluded features such as glove boxes and audio and our modern dash design. Perhaps I'm inventing a problem to solve. We will wait and see how it performs.

[GoDadGo]

Chris,

Stuffing 10-gallons of stuff into a 5-gallon bucket always stinks.
Why not come up with a design that places the HVAC behind the seats?
Create a POD that holds a receiving system large enough and then run the ducts forward.
You've got tons of room there, plus it would allow you to even run ducts to the seats to cool them too.
Seeing some of your modern interiors in your cars tells me you can easily pull this off.
Building these kits would be child's play for you once you perfect it.
Besides, who says the HVAC must be stuffed in the dash anyway.
Think outside the box and a very cool box it will be!
I know if anybody can do it, you surely can!

Good Luck From The Out Of The Box Darkside Guy!
..I'm always going outside of the box & always going in the opposite direction!

.....................https://youtu.be/A0Jb1tjjtPU

Steve
aka: Heyoka
1st Time Darkside Builder

[Chris @ Forma]

Steve,
In the back is actually where we started. Plenty of room to packaging the air box in the back, the challenge is there isn't enough space to package the ducting in the tunnel. If the damper system is in the back, need three ducts running forward floor heat, dash a/c, and defrost. If we put the damper system forward, we are back to packaging problems under the dash. It was also looking as if it was going to be a more expensive solution.

Also, we believe this design, rather a variant of it will fit in roadsters as well.

I have one of these running on the bench and it works really well at least from an airflow standpoint. I'll post some pictures later this week. We are also working on cooled seats for another build. Hope to be able to offer these also as a kit.

[Just puttering]

On a cold wet winter morning, you will want outside air for defrost? At least with a DD, I dont know about the Coupe!

[Chris @ Forma]

With Defrost we run the compressor and the heater core to dehumidify the air. At the bottom of the core box we collect condensate and drain it outside the passenger compartment with a small hose. The only development piece is the micro-controller that will manage the system. My Electrical Engineer is tied up on other projects so it will be a couple of weeks before I can put this on his plate.

[Alphamacaroon]

Looks really really nice! My personal concern would be that there is no way on my build I would be able to fit all that ductwork behind the dashboard. Even with the flexible tubing that FFR supplies, I had a really hard time finding enough room for everything behind the dash.

Oh, and where would the wiper motor get mounted with this configuration? Is there still enough room to the side?

[Erik W. Treves]

I have mine in the back with the intake pulling the air from area under the glass hatch -

https://thefactoryfiveforum.com/attachment.php?attachmentid=68481&d=1496451234

The issue I have is that I have black carpet and horizontally position rear hatch - so in the heat of the day the area in the trunk get HOT and then gets passed to the HVAC - and the amount of cold air needed to move that heat mass isn't an easy solution.

I have been toying with the idea of putting some carbon clear tint on the glass to help reflect some of that energy... I would say that I am still able to remain comfortable in 100 degree days - or at least not pouring sweat...:)

this installation looks like it will work - would like to see it modeled with the wiper system in there - also it seems to remove the option of mounting the ECU in the firewall

my .02

[Chris @ Forma]

Jim,

The primary driver for pushing the primary distribution forward of the fire wall is to allow more room under the dash. In our design, heat is fed directly to the footwells so as to not take any space under the dash The AC after passing through the firewall sits right on top of the 1-1/2" tube that the firewall is attached to...only takes up 1/2" rearward of the tube. We have a good sized glove box on the passenger side. also our dash sit further forward than the FFR dash so we have even less space. The only hoses we are intending to use are about 6-8" long to connect the duct to the outlets (dash and defrost) the only reason for this is to make assembly possible. Otherwise it would take 8 or 10 hands to install the dash.

I hope to have one installed in a client's build that is our shop right now. HVAC is on hold for a couple of weeks as we are wrapping up our coupe window solution. We aren't quite done and we already sold 5 plus our coupe.

Erik, I've always loved your build. Absolutely spectacular. We started off trying to get it to work in the rear. We just couldn't make the duct work package through the tunnel and feed our dash. We put too much crud in the way. I hadn't even considered the greenhouse that follows behind in these cars. The other thing we found is that at a standstill (as in traffic when you really need it) the tunnel gets really hot. On another one of out builds where we put the A/C in the rear, the air entered the tunnel at 50 degrees F and exited the dash at 75-80 degrees. Not exactly what we planned to have happen.