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rebuilding hvac system how to with pics

Wookalar

Well-known member
Joined
Nov 27, 2013
Messages
458
Location
Arizona USSA
While I had my dash apart for the pedalbox removal/upgrade I noticed a lot of nasty dirt in the various openings in the hvac system, so I decided that I would go through it and clean it all out.

The biggest issue I encountered was trying to find the open cell foam with adhesive on the back. Sure you can buy the 1/2 inch by 1/4 inch weather stripping at the hardware store but in terms of larger size such as 6 x 3 which is about the size of the trap doors inside the box, I have not yet found a source for that foam with adhesive.

I ended up just using the foam weather stripping I found at the local hardware store, and I cut strips to fit the flaps.

Here is a pic of the dirty blower motor box before. click

As you can see, the various foam inside and around the opening is pretty nasty. There are two different size foam used in our HVAC system, one side of the trap doors had a 1/4 inch depth foam, the other side had 1/8 inch depth foam (rough estimate).

Items needed for this project:

phillips screw driver
pick
vice grips
vinegar
some Tupperware for soaking the metal
baking soda
spray paint
wire wheel/dremel
3/8 x 1/2 inch open cell foam tape
3m super 77 adhesive
silicone based grease
masking tape
scissors
blue medium Loctite
metal polish
Lysol or fantastic anti bacterial cleaner

Begin by disconnecting the electrical connector and removing the 3 screws that hold the motor into the box. I had my dash out so it was easy for me to access the bolts that hold the actual box to the bulkhead.
DSCN5327

Even some rust build up, not something I want in my HVAC.

DSCN5340

Remove the gold screws that hold the two main plastic pieces together, and pop off the one clip. The unit will pull apart into two pieces.

DSCN5352

Remove the one screw securing the circular flat metal panel to expose the inside, then you can see the trap doors. Remove the two screws holding each flap to its rod. I used vice grips for this part rather than a phillips screw driver, I didn't want to take any chances with damaging the screw head and not be able to get them out.

DSCN5360

With the screws on each flap removed you can lift them out of the box. Now look at the lever on the outside of the box. Carefully remove the plastic clips from the arm and remove the screw holding the plastic white washer and the silver bracket. Now pull the rods out but take notice of the tab in the middle of each rod. Line that tab up with the hole and it will slide out.

DSCN5402

Now comes the fun part, removing the adhesive from the metal flaps. The foam pretty much dissolves under water and light pressure from your fingers, the adhesive is the real pita. I tried to wire wheel the stuff off and it really didn't want to budge so I ended up soaking it over night in vinegar. The next morning the adhesive had lifted off the metal entirely and looked like snake skin floating in the liquid. Follow up with soaking the metal flaps in baking soda and water for a few minutes or so to neutralize the vinegar.

After a day of drying I wire wheeled any corrosion off the metal flaps, wiped them with laquer thinner and then I sprayed them with clear rustoleum paint. Now is a good time to also put that circular panel to the wire wheel and remove any rust that might be on it. Once that is done hit it with a few coats of paint.

Once the trap doors are dry you will be ready to apply your new foam. While picking up the foam at the store I also grabbed a can of 3m super 77 spray adhesive. Cut your foam weather stripping to length of the flaps. Tape the flap where you don't want adhesive, then spray the adhesive on with a LIGHT coat (there is already adhesive on the foam, I just decided to use some more just in case). Wait about 30-60 seconds for the adhesive to get tacky then carefully but quickly apply your foam strips.

IMG_7180

Lube up the rods only where they will be touching plastic, you don't want grease anywhere it's not supposed to be so it doesn't collect dirt. * DO NOT * use a petroleum based grease, it will break down the plastic. Use only a silicone based grease.
 
Last edited:

prove_it

Well-known member
Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
Might be able to get it from Mitsu.
 

Wookalar

Well-known member
Joined
Nov 27, 2013
Messages
458
Location
Arizona USSA
Ok, I only scouted around HD for a few minutes but I swear that I have seen somewhere before this spongy open cell porous foam with adhesive.

I bet 3m probably makes some too, just a matter of finding it. Surprising that some auto places don't sell this stuff. I hit up michaels crafts and hobby lobby and they didn't have anything close.
 

turbowop

Well-known member
Joined
Apr 29, 2001
Messages
11,972
Location
Yakima, WA
I've found all sorts of one sided sticky foam at smaller hardware stores. Like an Ace Hardware or something similar. Kinda the same way they have a much larger/better selection of loose screws/nuts/bolts/anchors/etc, they also have a larger selection of sticky foam. They have the open cell porous stuff fosho.
 
Last edited:

Wookalar

Well-known member
Joined
Nov 27, 2013
Messages
458
Location
Arizona USSA
Word I will see if Ace has something that would work.

I ordered some of that regicell foam this am so maybe I can just use gorilla glue. /ubbthreads/images/graemlins/dunno.gif We'll see.
 

BoostedAWD91

Well-known member
Joined
Mar 1, 2007
Messages
2,937
Location
Danville,Pa
hardware stores sell it and i think you can even get it at walmart. Its used to seal up doors or windows.
 
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