vent/bi-level air flow

mhamilton · Posted: Mon Aug 13, 2007 7:27 pm Post subject: vent/bi-level air flow

I have an '80, and everything works as it should, but I have always wondered why so much air comes out of the floor vents in Normal or Vent mode. The factory service manual says there should be a slight air flow, but in mine the same amount of air comes out the floor in Normal as in Bi Level mode.

When I had the plenum open to clean the evaporator, I could see the heater mode flap, and it had a large gap all the way around it. Should there be some kind of foam or rubber seal on it? I know the dash vent flap has a rubber seal all around it, but there was nothing like that.

The lower mode door does operate fine, it just doesn't seem to have any effect on stopping air flow to the floor vents.

Thanks for any help,
-Michael

mhamilton · Posted: Tue Aug 14, 2007 9:21 am Post subject:

I got it figured out....

I was reminded that foam had been coming out of my heater vents a few years ago. I pulled the heater outlet and looked into the plenum, and sure enough, the lower mode door is covered with foam on the bottom side. Mine is missing half the foam, so it's not sealing anything anymore.

Hopefully I can figure a way to repair this without having to pull the dash.

-Michael

mhamilton · Posted: Tue Aug 14, 2007 2:54 pm Post subject:

Here is the repair:

First I removed the heater outlet vent, held by two 7mm screws. One behind the radio, the other on the passenger side corner. Removal is made much easier by first removing the ash tray and the radio.

Once that is out, you can see the lower mode air door and what is left of the foam. Before Picture

It helps to have a hand held vacuum pump connected to the actuator (where yellow line connects) to move the door up and down. The old foam disintegrates when touched, so removal is not a problem.

I used some scrap sound deadening material, a 1/4" foam rubber. In this picture is my rough cuts, should be about 1/2" shorter longways. New Seal

Finally, I used a couple dabs of weatherstrip adhesive to stick the new piece on the door. Held it in place with a bunched up shop rag while it cured (stuck pretty well by itself, though). [color=blue]New Seal Installed

What a difference that makes! Now in Max, Normal, or Vent modes, no air comes out of the floor vents, all of it comes out the dash. In Heat mode, all the air comes out the floor. And in Defrost, it will make quick work of defogging the window this winter!

Cabamino · Posted: Tue Aug 14, 2007 3:31 pm Post subject:

Thanks Michael for the info and procedure. I'll be fixing mine tomorrow. My kid was complaining his feet were freezing when we went on a trip last week.

Jerry
_________________
1980 Caballero
1980 El Camino Conquista

mhamilton · Posted: Wed Aug 15, 2007 11:13 am Post subject:

Glad it helped, I hope it takes care of your bilevel control.

The original material seemed to be 1/8" thick open cell foam, but I'm not sure where to find that. The foam rubber I used seems to be working fine so far.

mca_daddy · Posted: Fri Sep 12, 2008 9:32 am Post subject:

I know this an old thread but I thought I'd post an idea. I'm trying to do the same thing to my floor vent since the foam has deteriorated. In finding a good insulator, I ran across some air conditioning (residential type) insulation tape in my garage. It is about 2 inches wide and comes in a roll of about 20 feet at Home Depot. It already has adhesive on one side and is about 3/16 thick dense foam. It is easy to stack layers. I'll let you all know if it works. Started the little project last night but I can't seem to get up in there to really see what I'm doing (after accessing all that was mentioned above).

galangmaid · Posted: Fri Sep 12, 2008 10:57 am Post subject:

I would be interested in knowing how that worked out for you Mario.

Gary