I'm currently *****-deep in replacing my heater core and have come up against a bit of a stumbling block, and hope one of you with more experience can give me some advice. I've got all 7 screws out of the heater core case and it's almost free but the air duct that attaches to the window defrosters seems to be in the way. This appears as #45 below.



I've seen some owners who advise to simply cut this duct and then reattach it with tape, but I'd like to avoid doing this if possible. As you can see I'm really close...



Is it just a matter of maneuvering the cover out past the duct? I don't want to force anything or do anything stupid after getting this far. Thanks.

 

It's been quite a while since I had to replace mine, but I don't remember cutting anything. There was certainly a lot of prying, tugging and cussing!

 

My son & I replaced ours in December. We have 95 as well.

What is not shown in the break down photo is the defrost duct has another duct attached perpendicular to it. This duct extends into the main cover of the heater core. The duct snaps onto the defrost duct work. As you attempt to remove the case from the heat core, the duct on the perpendicular to the horizontal defrost duct prevents you from lowering it.


Our 95 has manual heater blend door. The heater blend door cable had to be removed from the top of the heater core cover. I’m not sure how or if the auto climate control is different.

What worked for us was to remove the defrost duct at the passenger side. This gives an extra inch or 2 of movement for the horizontal duct. Spray the horizontal duct where it attaches to the heater core case and the perpendicular duct silicone or ptfe spray. If you lay on your back and look up, you will see the perpendicular duct where it attaches to the defrost duct. You can use a flat blade screw driver to pop it off or just pull the horizontal defrost duct up and the case down and it will pop off.

To reattach everything, we placed the heater core cover without attaching it. Then we put the perpendicular duct (I’m going to refer to it as pick up duct), in side the heater core cover and fed it up to the opening with one hand. Then with your other hand grasp the pick up duct through the heater core cover opening. Next, I switched hands and held the pick up duct with my right hand on the outside of the heater core cover. Now, the left hand snapped the defrost duct on to the pick up duct. Finally, you can reattach the heater core cover and the duct.

I hope this makes sense. Once you have it apart it will be clear.

We couldn’t get enough room on reassembly to put the pick up duct externally. It had to be placed inside the heater core cover first. There just is not enough room even with the passenger side defrost duct removed.

 

Those ducts were 'fun'. Endless prying and I was sure something would break. Took ages too. Reassembly wasn't any better and I understand why many recommend cutting.. and at one point I remember thinking I might have to. The box does come out and goes back without any cutting though you'll use all rude words you know.

 

This is where the duct in question enters the heater core case. There doesn't seem to be any room to move this duct away from the case in order to lower it as it's wedged in tightly behind the center instrument console even when the right side is disconnected. Maybe I just need to pull on it harder. Is there a pipe behind that flange that goes into the heater core case? There seems to be, as the cover doesn't appear to want to just slide down off of this flange.

That said, overall, as long as you're not attempting to get a daily driver back on the road over a weekend, this job hasn't been that bad. It only involves undoing screws, bolts, and electrical connectors, requiring basic hand tools and knowledge that most any home mechanic likely possesses. I would encourage anyone contemplating this job to go ahead and do it. I've always enjoyed knowing what was going on under the skin of my cars, and the knowledge gained makes driving and owning these cars that much more enjoyable. Plus there's plenty of help around here if you get stuck -- like I am right now. LOL

 

I had to remove all ducts. Worked roughly as PatrickBowersJr described. Can't tell from the picture which one it was but one of the ducts had an 'extension' into the box and required quite a lot of movement to pop out/disconnect.

 

You are correct. There is a duct connecting perpendicular to the defrost duct on a flange. It is snapped on.

I gained an inch by disconnecting the passenger defrost duct at the side grill. Instead of trying to pull the cover down push it up and back above the heater core. It will give you some room.

Finally you can place a large flat blade screw driver blindly behind the flange and twist it to try to get the duct to pop off.

 

You should disconnect the vacuum hose crossing the cover and the yellow air bag harness. It will give you more room

 

Up instead of down; I'll try it.

For those following at home, the duct in question in that football-shaped flange with the screw hole. This is where it attaches to the back (removable) half of the heater core case.

The vacuum line is disconnected. It just got in the way of my quick picture.

 

You might be able to reach in blindly behind the cover and grab the duct. I did not see duct on any of the manuals so I didn’t know it was there either.

 

Success!

What ended up working was rotating the cover 90 degrees clockwise, so the little extension of the duct that protrudes into the cover didn't have to come out after all. This gave access to the three 5.5mm screws that held the heater core into the case. Thanks for all who helped! Once I get everything core-related buttoned back up, I'll remove the rest of the carpets for cleaning and see about putting some Fatmat sound absorption down. So glad the hard part is behind me!

And for all future readers of this thread, this is what the hullabaloo about the flange duct was about. Photo is of the back side of the heater core cover showing the extension that goes into the plastic box, making trying to remove the cover more difficult than it should be. LOL And as PatrickBowersJr indicated, I have not seen this piece on any of the schematics showing 1995 Corvette heating/AC ducts.