Coupe HVAC Duct Routing and Custom Plenum

[TTimmy]

I thought I would share my dash HVAC vent routing including a custom “plenum” build. I saw some other designs in the forum that would have worked – I decided to go a somewhat different route.

My goals are 1.) to reduce and simplify the duct routing behind the dash and 2.) provide a way to shut the dash vents that are shared with the defrost in order to improve its effectiveness when needed. I am feeding four dash vents plus the two defrost vents.

I used 2” PVC “T” fittings and a bit of 2” PVC. In order to get all the bits together I needed to trim back the “T” fittings and also resize the opening to accommodate a direct connection to the FFR vents and FFR step-down needed to connect to the defrost hose. I was able to accomplish this with a hole cutter on my drill press. Not the most glamourous approach but it’s what I had available.

Happy to post more pictures if anyone is interested in the detail.

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[Jphoenix]

Nice!

[aaron44]

Do you have a way to shut off the defrost vents and run full AC?

[DW66]

I have a roadster with A/C and have not hooked up my defrost vents yet because I haven't been able to come up with a good way to shut them off. I'm interested to see what other people have done for this.

Dave

[aaron44]

DW66, all I have to go on right now is some advice from Henry (65CobraDude). He has done it before but didn't document part numbers or have pics. I've got a 2" waste gate valve that I'm going to try to make fit behind the dash. If it works, I will post part numbers, etc. but I still haven't been able to find where someone has done it. Maybe by next week I will have either succeeded or given up.

[TTimmy]

I did not add any way to shut off the defroster vents as built. One thought was to have someone with a 3d printer create a cover that could clip into the existing defroster vent. It could be quite low-profile and unobtrusive. Most of the time these "covers" would simply sit in place, thus they would not be in the way or bouncing around in the car. All that said, my car is still up on jack stands so not an issue at this time.