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Just finished rebuilding the heater core assembly. I pretty much just followed the thread instructions, but I had a couple of things to add.
I ended up using contact cement to stick the foam to the plastic flaps instead of using 3M spray, mostly because it's far less messy. I coated the plastic flap and also the adhesive side of the foam I was using. I know it sounds weird to be painting contact cement over the adhesive, but this stuff needs a layer on both sides (dried) to work. And it worked fabulously. Instant bond, and it sure feels as if it's not coming off. It worked so well I even plugged the holes I cut wrong for the pegs.
I also found that a lot of my hardware inside was covered in rust. I used Evapo-Rust to dissolve away the rust, and then zinc plated it using supplies from Amazon (power supply, buckets, wire, zinc bars) and gold chromate solution from Caswell Plating. I also used a gallon of muriatic acid from a pool supply store to dissolve the old plating and etch the metal before replating. It's a lot more work but I'm trying to restore the car without resorting to spray paints. If some of the smaller pieces look uneven, that's because if you want a shiny finish, you need to polish out the parts and I just wasn't going to sit around with a Dremel trying to do that to screw heads and the metal connecting clips.
So I did not realize after all these years, the heater assembly was contained in the RX7electrical troubleshooting book, not the factory manual. I scanned the page so everyone can have a clear copy suitable to print.
Hello Fellow FD HVAC Rebuilders! I recently followed this thread to help assist me in picking the correct foam for the blend doors that don't cost an arm and leg. I purchased all of the materials from McMaster, even some extra for comparison.
PN: 8709K42, 1/2" Wide x 1/4" Thick x 50ft Roll (For Mating Surfaces) May Be A Bit Thin PN: 8614K81, 54" Wide x 1/8" Thick x 1ft Adhesive Backed (For Covering Wire Harness) PN: 85175K23, 54" Wide x 3/16" Thick x 1ft (For Blend Doors)
The original poster and many others used PN: 93625K194 6" Wide x 5/32" Thick x 10ft Adhesive Backed Gun Rubber Foam, but most complained about it being too stiff but right around the correct thickness, I purchased both for comparison and for the following reasons I picked the 85175K23 foam instead. It is a softer foam to compress easier to create a tight seal, it is also oil-resistant and my biggest plus is being flame-retardant! The only down side is that it is not adhesive backed so they will need to be glued down using some kind of polyurethane type glue, although the original poster did mention that they had to adhere down the adhesive backed pieces anyway as it wouldn't stick well to begin with.
For an adhesive recommendation I would likely say try something similar to a contact adhesive like woodweld contact cement (I believe is also what the original poster used), I tried using E6000 and it works well once stuck down but the application process for it is less than ideal for the semi large surface area the blend doors have.
For the flaps/doors with all the nubs on there that people are cutting/working the foam around, I studied the functions of all the doors and could not find a particular reason why those would need to be on there (does not add stiffness, does not come anywhere near a sealing surface, etc etc), so I took some flush cutters and cut them right off to help save time with foam cutting and removing the old foam. I'm sure someone will tell me how dumb it was to cut those off haha!
Hoping this can help someone in the future be more confident in their material purchases when tackling the job! In the process of developing a ABS 3D printable AC evaporator case/delete duct as Mazda use to make FD01-61-150B and sell it for around $50 but now the cheapest I can find a hollowed out evaporator box for almost $200.
Awesome work guys, make it easier on yourselves when notching out with the exacto knives on the flaps. Just mark the tops with a color or paint then lay them on get your template and drill each hole out of the foam. Should take less time!
