Fresh Air Inlet Door
With a heat gun at 550 and a thin putty knife, I removed the blower motor mounting panel shown at right. Though the bracket didn't slide in as I thought it would, having this panel out made installation easier by allowing access to the space behind.
Next I set the heat gun on low and cleaned out the yellow sealant with a putty knife. Be sure to get all sealant out of the bracket mount point located behind the firewall and just above the kick panel vent hole.
I used the same technique to remove the Astro vent. Obstructions prevented me from getting the putty knife completely around the inlet. To finish, I held the heat gun as near as possible to remaining area. After about two minutes, I tapped the vent from underneath with a 4 lb. dead blow hammer and it popped out. The vent'a adhesive lip had softened and broke off.
I fit checked the fresh air inlet bracket, and that's when things begin going sideways. The first try failed because the bracket didn't fit past the kick panel vent port. I got the brilliant idea to removing some of the vent port. After cutting a section out with a dremel cutting wheel, the bracket still didn't fit. Removing more material didn't work, and I erroneously concluded that the vent port must be removed. I won't go into the gruesome details here, but I posted a walk through for repairing that unfortunate piece of hardware. (vent port repair)
After all that, the bracket still didn't fit. That's when I understood it was too large for hole it needed to pass through. The short, vertical side contacts the back of the open space before the front clears the firewall. Bracket alterations must either remove the short vertical side and part of the bottom, or shorten the box height. I shortened the box as shown. In retrospect, cutting the firewall would've been a better approach.
Before cutting the bracket, I fashioned a jig from 1/2" steel flat and used M6 machine screws to secure it. After grooving a piece, I bent it to follow the bracket's contour. I drilled screw holes in the jig, then clamped it to the bracket and drilled screw holes in the bracket. After cutting and reassembly, I used lock washers so the screws would stay in place finger tight. In the picture, a small gap in the bracket halves represents material removed by the cutting wheel. It's important the bracket maintain its original lines and dimensions so the fresh air flap seals properly.
I placed the pieces behind the firewall and assembled them for a fit check. You can see the hardware, and I was concerned this would interfere with making a good adhesive bond and with fresh air inlet operation. I decided to remove the hardware and fill the holes with a structural putty.
Filling the gaps is much easier said than done. I used aluminum tape so the putty doesn't bond to the car. Be sure to only tighten the nuts finger tight because you won't get a tool on the screws. I was careful and did not get any putty on the threads. Had I been smarter, I would've covered the nuts with masking tape.
I made structural putty from epoxy (West 105 System), colloidal silica (also from West) and 1/32" milled fiberglass (from Fibreglast). I added silica and milled glass at 2:1 into the epoxy until it was the consistency of frosting, and smeared it into the gaps with my finger. After 24 hours, I removed the tape and hardware. It's a tight fit, but if you take your time, it can be done.
It's easier to seal the Astro vent hole before inserting the fresh air inlet bracket, but I got so absorbed with getting the bracket in I forgot about it. It's very straight forward and you can click through the series on the right to check it out. I used aluminum tape for backing material (top L & R), cut four squares from a piece of 4 oz fiberglass cloth, and abraded around the hole with 36 grit sandpaper. I mixed a batch of epoxy and added colloidal silica until it was a ketchup consistency. I laid the squares in from smallest to largest. Note how colloidal silica makes the epoxy mixture white after it dries.
I used Evercoat SMC panel adhesive to adhere the fresh air inlet bracket in place. I applied it with a plastic putty knife and finger, trying to maintain a minimum 1/8" adhesive thickness. It's a very messy job because the space is so tight. I used a spring clip to hold the bracket in place while the adhesive set.
After curing, I used a mirror to inspect the bond. Some areas needed more adhesive, particularly the gap between the fender and bracket, and the gap at the end of the bracket. When finished, there was quite a bit of excess adhesive to remove.
I used a heat gun, flexible putty knife, razor, and exacto knife to remove the excess adhesive. The bracket has pass-through holes for attaching the flap, and it's important to ensure the mounting surfaces are clean or else the inlet flap will not seat properly, resulting in a poor seal. Also ensure the contact area between the inlet flap and bracket is free of adhesive. After a couple hours, I had cleaned the excess adhesive and smoothed / shaped what was left.
I did a fit check, and the fresh air inlet door scraped against the firewall. I was able to move it back some by loosening the mount plate hardware. Notice the slight notch in the door's top (upper left). It was there when I bought it, and helps clear the firewall adhesive seam contour.
Using a dremel tool and small, spherical engraving bit, I made a weep hole (lower left) to drain the trough (visible in picture at lower right).
Applying vacuum, I checked the seal using a bright work light. The fresh air flap is flimsy and able to conform a bit to the bracket edges. It's a pretty good seal.
I used SMC panel adhesive to reinstall the kick panel port and blower mount panel back in place. I cut 1/8" thick plastic washers for spacers so the clamps would't squeeze out all the adhesive.
SUMMARY: I'd rate this job an 8 out of 10 the way I did it. If I did this again, I'd remove the blower panel, clean out the old sealant, and remove the Astro vent inlet. Then I'd remove enough firewall to the left of the blower housing mount to insert the fresh air inlet bracket without cutting it. I believe this makes applying the adhesive easier. I also think repairing the cut firewall is easier than the jig rig I came up with.
This work is a necessary part of the Engine Bay and Firewall project, which is my goal for summer 2015. The remainder of this project is deferred until later, except for the Evaporator / Heater Box rebuild detailed in a different walk through.
Kick Panel Door
Cars without a/c have the Astro ventilation system, which includes two kick panel doors operated by cables. To convert, the driver side is removed and the port blocked off, and passenger side is automated with a vacuum actuator. The rebuild kits and vacuum actuators are available from vendors, but the brackets and levers are not. At right is one I got off e-bay for the brackets.
The doors consist of a foam seal layer sandwiched between to thin, metal plates. The brackets and plates are secured with semi-tubular rivets. I used a dremel and grinding head to remove the curled lip of the rivet and a punch to knock it out. There are seven rivets to remove. Once they are out, the two halves peel apart. I sandblasted everything, powder coated the door halves, and painted satin clear on the bare metal pieces.
For assembly, I put the rivet through the flap and used tape to hold it in place. Then I put the new foam seal in place followed by the other flap half. I used a small ball bearing to curl the semi-tubular rivet. I read about this on a forum, but did not have much luck with it. The bearing tended to slip, deforming only one side. I ended up using a punch to finish curling some of the rivets, which resulted in some splits. I think it will be fine for holding the halves together.
SUMMARY: This was very straightforward. I would rate it a 5 out of 10 the way I did it. I recommend getting a semi-tubular rivet tool to save yourself the headache of trying to curl these back with a bearing and / or punch. With the proper tool, this would easily be a 3.
This section should be titled "How NOT to Install a Factory Air Conditioning System". At least that's how it started out, as you'll see below. My car is one of a handful of 79's delivered without air conditioning. That was the last year it was optional, and I don't know whether the original owner was interested in performance or just cheap, but the cabin gets miserable during the midwest summers. Here are the things I considered:
AFTERMARKET DIRECT FIT KITS: When I started this project, direct fit kits like those offered by Vintage Air were attractive, but only available up to 1976. UPDATE: Since then, direct fit kits for 77 - 82 models are available, but I already completed the modifications necessary for a stock a/c system and purchased the components.
UNIVERSAL A/C KITS: I checked out some all-purpose vacuum controlled systems, but they require placement under the glovebox, an area already limited in foot room. Additionally, it seemed interior modifications, such as cutting holes in the glove box, were required for these systems. None of them made provisions for heat. Now I rarely use the heat, but it is nice cruising with the T-tops off on a brisk fall evening with the heat running.
STOCK RETROFIT: The only remaining solution I was happy with was installing and upgrading the factory a/c. I believed that with the car off the frame, it would be a fairly simple undertaking. I didn't know what I was getting into at the time...
First challenge was parts availability. I scoured the internet and found no after market vendor for the fresh air inlet bracket, either half of the evaporator box, the linkage and bracket for the passenger kick panel door, the interior heater box, the heater / defroster duct assembly, the center duct, or the defrost duct. I acquired these from e-Bay vendors / members, and forum members. These are used and some require repair.
Research indicated the fresh air inlet bracket would be the hardest part of the retrofit. For those that don't know, it's on the passenger side, tucked way back behind the cowl screen. It is not required to equip the car with a/c, but is necessary for the "Max AC" option to work correctly. When "Max AC" is selected, the fresh air inlet flap closes and the kick panel door opens, causing cabin air circulation through the evaporator box. Posts I read involved inserting the bracket from the cowl. Since I had the car on a body dolly, I removed the blower motor housing mount panel from the firewall to insert the bracket that way because I thought it allowed more room. As you will see, it did not go as smoothly as intended, and I'll briefly summarize what I would've done differently so others can learn from my experience.
Modifications: Four
- Enlarge hole in firewall to accommodate evaporator box
- Install fresh air inlet support bracket and hardware (e-Bay)
- Install kick panel port bracket and vacuum actuator (e-Bay)
- Cover driver's side kick panel port
- Plug Astro Vent holes
Upgrades: Four
- Install blower cage from C4 (AC Delco 15-8418)
- Install Sanden compressor
- Install parallel flow condenser
- Cover blower motor and evaporator housings with thermal paint (Hy-Tech Metal Shield #1267)
Air Conditioning