Heater box removal , A/C 1980 F body

[shadango]

So we have come to the conclusion that we need to drop the heater box to get to the underside of the cowl........I stuck a hose up in the cowl and water starting leaking from the heater box area.....so clearly there is an issue there. We dont think its rot necessarily, because the cowl is in great shape....thinking MAYBE it has to do with the seam that the fresk air "horn" makes with the cowl.

Wondering...is the glove box insert removal like on my 72 cuda and if so can anything be seen "behind" it as far as the cowl, etc? As it is the heater box completely blocks any view at all.

The car has A/C and I know that makes it more fun....

But has anyone done a write-up on this job?

Planning to replace the heater core and A/C condensor while we have the box apart.....unless we can figure out a better way to seal that area so we can avoid dropping the box.

The box on my non A/C Cuda is easy as pie......on the 1980 Volare, it looks like it will be a lot of fun.......

 

[slant6billy]

Sir- Here you go:

 

[BudW]

I have done the job quite a few times. Not easy – but a FAR FAR cry easier than most of today’s vehicles are - so not hard either.

Before doing anything – yet, there is a large hole in the passenger side of cowl (about 6 inch rounded corner rectangle) – so if water is sprayed into the cowl hole area sideways, water could be allowed into the evaporator case.
I do not see that area rusted out - so if yours is, I would be surprised.
With that said, there are 3 flaps for water drainage. I do see (often) debris stopping those drain holes up - so a shop vac is helpful and some water to get the drains un-clogged.

If car has the Vent box on driver’s side, then you could have two large holes in cowl area.

During a heavy rain and if parked at a slight angle, I occasionally get water into the cabin of my 5th Ave, for the A/C drain tube can only allow so much rain water out.

In my opinion, the only real hard part about evaporator case removal is the fact it is a large case and getting it out solo, and without a lot to grab ahold of, is one of two hard parts. This is not difficult, per se, but awkward.

The other hard part is getting to the 4 (I think it is 4) stamped steel nuts on engine side of fire wall, behind the engine. Again, not hard - but awkward.

The important part is to bag, and tag, your fasteners.
A cordless screwdriver can make the job a lot less painless.

If heater hoses have not been off of the heater core - in a few years, then cut a slit in hoses and don't try to re-use old heater hoses. It is not worth the effort to save the hoses (too much time spent and nothing will come of it). If hoses are fairly new, then OK to save.
Old hoses have a tendency to weld onto the copper pipes.
BudW

 

[shadango]

Sir- Here you go:

Thanks man...I also found another forum where a guy lists out the steps with some pictures for the a Diplomat (dippy.org).

 

[shadango]

Before doing anything – yet, there is a large hole in the passenger side of cowl (about 6 inch rounded corner rectangle) – so if water is sprayed into the cowl hole area sideways, water could be allowed into the evaporator case.
I do not see that area rusted out - so if yours is, I would be surprised.
With that said, there are 3 flaps for water drainage. I do see (often) debris stopping those drain holes up - so a shop vac is helpful and some water to get the drains un-clogged.
BudW

Thanks Bud.....yeah we investigated the flaps and looked for debris already......I even stuck a flexible camera snake up in the cowl area...I dont see any rot.....but it did look like MAYBE the seam sealer around that intake air horn that you described is cracked........

 

[shadango]

Wondering -- once you pull the top dash cover/pad out, is there any access to the "air horn" part where it meets the cowl? Seems at first like the box would be mating with it from below...... but at 35:02 in the video, it shows a large square hole with a small round hole below it......I assume that is where the box mates to the firewall....

So I guess the air inlet make a right angle with the firewall and then mates to the box??

While we will want to replace the heater core and ac condensor at some point down the road its fine right now and if we can get away with NOT having to completely pull the box just to fix the water leak, MAN would that be great,,,,,

 

[shadango]

After watching the video again and realizing how much has to come out......cutting a hole above the top hat in the cowl isnt looking so bad now....LOL

 

[BudW]

That “hole” is not in your line of sight and honestly, I don’t remember looking up at one.

I have traveled through body shops and seen the cowl/firewall areas cut into – so I know what they look like from the “unseen” side.

This picture should help a person visualize it better.

Note, the 3 flaps (part ID # 10) are the low points of the cowl – which allows for water drainage.
Normally, the “unseen” area does not get any paint, and how this area doesn’t rust out more – IDK.
BudW

 

[BudW]

Note: getting the “crud” out should help the water leak the most. If those 3 flaps are stopped up – there is no place else for water to go to.

I live in a forest (in the middle of Oklahoma City) and I have to clean out that area every two to three years.









A satellite picture of my home with 1 acre of rather tall white oaks, from Google Maps. You can even see a lengthy shadow on roof of my house (red circle).

 

[shadango]

Note: getting the “crud” out should help the water leak the most. If those 3 flaps are stopped up – there is no place else for water to go to.

The flaps are the first thing we looked at.....there is no junk in the cowl area at this point....there was a small amount but not much.

We used a flexible camera snake to look into the unseen areas and I see no rust or rot at all.......all I can see is that the sealer around the "top hat" where it joins the cowl seems cracked.

Dang it, this sucks. Seems like the only real option here is to cut open the cowl.....our is seemingly perfect paint wise and I hate to hack it.

 

[BudW]

Were you using a water hose, at low pressure, to look for your water leak?

 

[F body Deconstructor Jim]

 

[BudW]

It doesn’t get any better than that!
Thanks Jim!


Jim, do you use a spot-weld drill bit for those?
Whose bits do you recommend using?
BudW

 

[F body Deconstructor Jim]

Bud I started off using the Blair Tool Rotabroach bits but found they were too brittle..and expensive. Catch a bit of the edge of a mig weld and it would shatter. I'd go thru 2 or 3 per vehicle at $9-$10 each.
Been using the Harbor Freight 2 sided spot weld cutter for years now. They were $3.99 when I started buying them and now they are $4.99. I go thru 3 or 4 per car max.
They are cheap enough where I dont feel bad tossing them in the trash when they get dull.
I think I still have at least dozen broken Blair bits. Not sure why I kept them...lol

BTW...heres the pic you requested...

 

[shadango]

BTW...heres the pic you requested...

View attachment 20274
View attachment 20275

Do you by chance have a picture of the interior compartment (rather than the engine side) side of the "air hat" area?

 

[F body Deconstructor Jim]

Not from that specific car...but here's a couple from an 80 F body that was converted from heat only to a/c...

 

[F body Deconstructor Jim]

If you need a more specific picture I can get one but it wont be an 80.

 

[shadango]

Thanks......trying to see what we will see if we go thru the huge headache of pulling the heater box.....it is looking like the b only best way to get to the leaky area, really will be from outside/thru the cowl.

 

[BudW]

Jim, thank you for the additional pictures.

This is the view I normally see and at this point (and not in the direction of arrow), I rarely look upwards at this point (not really a need to do so)

I would "assume" any year F or M body cowl air horn area would be pretty much the same.

Where the A/C or non/AC heater box attaches to firewall (or the ’76-79 A/C bubble) would be the primary difference – but that is not in the area you are looking at.


I’m planning on converting my ’77 no/AC wagon to ’80 up style A/C (thereby not messing with the ’76-79 A/C firewall bubble) and was wondering about how much firewall difference there would be tween those two were.

My initial thought is to get an A/C firewall, cut out the needed section and weld it in place on existing firewall. Still scratching my head on that one, though – but cutting/welding would be the best method.


Also considering adding a no/AC Left side vent air box onto my ’86 5th Ave (I love that thing on my previous cars). It appears that may require a lot more work to do – much like what I suspect Shadango is looking at repairing, maybe (on the Right side).
That would require a second air horn to be installed – and I don’t see how that could be done easily as I had thought.
BudW

 

[shadango]

I thought I would follow up on this thread....(seems I have several threads on various issues still in limbo due to no progress... )

Anyways, we retested the idea that we had water coming in around the cowl air hat.

We were much more careful this time with the water flow.

The car was parked facing downhill on the driveway and we trickled water in around the cowl area and watched for leaks. NOTHING.

Then I plugged up the cowl drain and let the water fill up so that water was above the seam sealer that seals the air hat to the cowl itself....confirmed this using a harbor freight flexible camera....actually had the camera under water looking at the side of the air hat.....no air bubbles coming up like a leak would cause, and no leaks inside at all.

Due to the slant of the driveway we could only test the FRONT half....so then we turned the car around and tested the REAR half....same process and same results.

Our cowl is NOT leaking. Glad we tested again before ripping out the heater box.

I think what happened last time when we got water "from the cowl" is that I was overzealous with the hose and got it INTO the air hat.

So moving back to the out side we chose areas and used a much lower and more concentrated/carefully aimed flow of water on various areas....

We are back to the seam on the floor pan I think.