So my kids destroyed and threw away the white foam piece that is at the base of the evaporator in the ac/heater housing. I have been searching all day and have found absolutely nothing about what to do if you can't use the old one. I've got an idea to use more of the rubber seals around the outside base (not directly on the bottom) but I was wondering if anyone else had ideas, especially if you had to replace it with something else. I was thinking about heading to the pick and pull tomorrow but I'm not very hopeful to find this piece.

The questions I'm pondering are: 1. How do I make sure I don't trap water underneath the evaporator or block water that may need to escape without sacrificing blocking airflow, 2. Should I put the rubber seals on the evaporator or on the bottom of the housing instead, and 3. Will the rubber seal strips be constantly in water when AC is running and will they stand up to whatever amount of water runs down the evaporator.

 

The local yard is a good start.

This is a rigid foam part? Could you make one out of a flexible closed cell foam sealed inside a plastic bag? Heat sealing plastic is pretty hard to do without the right tool. With the right tool a caveman could do it.

Making one from rigid foam would be more difficult. Perhaps you could press one with solvent. Get close to shape, plastic liner below a couple layers of paper towel with acetone in it, foam part, more paper towel and acetone, plastic liner, then the evap. That might selectively dissolve the foam at the pressure points until it slowly works its way into fit. Would be tedious and messy if it worked at all. Even more messy would be to fill the target space with a mostly sealed plastic bag, parts in place, then with a breather tube at one end and a can of 3x foam at the other... This will certainly make a huge mess and once that crap cures it is indestructible. Little known fact, alien spacecraft use this stuff extensively because it can withstand meteor showers, gamma rays, enemy lasers and torpedos, and cavemen. It was first recovered in Roswell by 3m chemists brought to anylze the wreck and they laughed all the way to the bank.

I would say the rubber parts are fine. Some water shut off valves have rubber parts inside.

 

FWIW
I recently did the heater core in mine and replaced the evap core just cuz. That thin foam sheet under the evaporator core had rotted away after 20+ years. As far as I could tell it has 2 purposes: to keep the evaporator from rattling around and to make sure there was a channel so the condensate could make it to the drain.
I used 2 strips of that closed cell insulation with the peel & stick stuff on it and ran them down the bottom length of the core, leaving a 1/2" or so channel between the 2 as a condensate path
So far so good.

 

Wait, are we working on a Jeep or a Space Shuttle? I think I was working the wrong problem.

 

Stay away from the new improved "green" foams that lack the CFC blowing agents. NASA did that, and lost the shuttle.
The original foam NASA used worked very well. But some environmentalist at NASA did not like the foam as it used CFC blowing gasses, so a new green foam was developed. NASA switched to the new green foam. It was noticed that after launches, the launch pad area had bits of the new foam littered about, it was falling off at launch, unlike the original foam that had the CFC blowing agents. Yes the new foam did not adhere very well to the fuel tank. This was shrugged off as acceptable.
Opps was that ever a big mistake.
And lets not even think about how stupid NASA was with using O rings below their rated temperature. Idiots!

 

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This white foam, is it rigid or squishy? is it styrofoam? styrofoam is rigid. kind of like cheap disposable ice chests are made of? this foam is generally closed cell so it wont absorb water (open cell does absorb water, like a sponge). Styro foam is often used in this application, seem it in many cars.

you may find sheets of styrofoam at Home Despot (Depot) in the insulation department. Hobby and Craft stores may also sell it it blocks. it maybe heat formed to some extent. cut with a bread knife or saw, or even melt cut with a hot wire. a package shipping store may also sell it as padding.
Or pick up a disposable ice chest at the 7-11 or grocery store, and cut it up if the size is right..

styrofoam comes in different grades, different density. likely in this use, it is a higher density end of the range as that will give it toughness.

TAP Plastic may also sell it., they are on the web.

of the good ole junk yard.

Given that these evaporators get cold, and thus water condenses on them, Id be inclined to think closed cell is way to go, as open cell will hold the water, which likely is not good (corrosion, mold, etc...)

 

Yeah, I'd definitely use closed cell foam over open.

And the Challenger o-ring issue was more of a Thiokol ****-up than a NASA ****-up, though NASA had a hand in it.

 

Thanks all! I'm going to try to find some of these things and see which idea makes the most sense. Really appreciate the help! I have a feeling that as soon as I get it all back together and running that one of my kids will find it in their room and be like "oh hey dad, did you need this"

 

NASA was warned, too cold for those O-rings. Warned by the people who designed it. NASA ok'd the mission anyway.

 

Was there some alien who said, "Hey Glork, don't fly around Roswell, they did a nuke test in NM and the fallout will wreck your anti grav system and you'll crash." And the AASA guy said, "Nah, it'll be fine."

 

Yup. That's the part they had a hand in.

 

I believe they were warned that pure oxygen at 1 atmosphere of pressure is REALLY dangerous as well. Pure oxygen at 4.5 psi is not nearly as dangerous.