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Old 09-01-2013, 12:58 PM   #1
Join Date: Sep 2013
Posts: 2
Replace black foam from AC vent

Like many TJ owners I'm getting open cell black foam from my AC vents. For those who have never seen it it is similar to the foam used in filters for computer chassis cooling fans (although probably made of a tougher polymer). I also have developed a leak in my heater core and will need to tear the dash apart to install the new one. So the questions are:
  • What exactly does this open cell foam do?
  • Is it worth replacing while I'm in there?
  • If it is not readily available from Jeep is there a good replacement?
My A/C does not appear to be blowing as cold as it used to, but I do see some oily residue on one of the A/C hoses. Is it common for the hoses on a 2001 to go bad (my jeep lives in the hot weather of the southeast). It looks to be a fairly extensive hose, and I'm a little afraid of what the replacement cost might be...


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Old 09-01-2013, 04:35 PM   #2
Join Date: Jun 2013
Posts: 502
That foam rubber is what is used to seal duct work and cases where they loosly fit/slip together. You can replace it with closely the same stuff from Home depot. Get 1/8-3/16 thick x 1/4 or 3/8 wide with self adhesive back. If you have the case out and want to replace all, all the duct work in the dash has it where they attach to the redgisters also. as far as the oily hose, yes it is starting to leak BUT it may only leak a 1/4 oz in a year-no big deal. When it gets too low and not cool good you can recharge with (1) partial can of 134a Freon. The factory hoses have these little pin holes in the outter sheath that will "bleed" oil if/when the inner hose lining starts breaking down. I wipe mine clean and keep and eye on it. I have yet to add any Freon and no telling how long is has been this way, last owner said he never had to have any added. Also yes it will be expensive, as the hose(s) and the fittings are a "unit". Sorry about the heater core. PITA to replace. And you will have to drain your a/c (Freon)to pull the case. What ever you do make sure you plug any a/c hoses/fittings after removing case to prevent air(moisture) from destroying the dessicant in the accumulator or dyrer. You will have to evacuate the a/c system before charging with Freon.

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Old 09-26-2013, 12:49 PM   #3
Join Date: Sep 2013
Posts: 2
How do I remove the AC vents to begin with? I know it is supposed to look easy with a screwdriver but I cant get it done.
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Old 09-26-2013, 03:43 PM   #4
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Join Date: Jul 2013
Location: Hurlburt Field
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My friend has a nissan altima with this black foam stuff sealing her air intake into the engine. Well, the foam has rotted away and was gone. Some black RTV worked fantastic to replace it. I'd be interested to see if that would work for you too ?
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Old 10-07-2013, 12:26 PM   #5
Join Date: Sep 2013
Posts: 2
Mystery solved...

The black open cell foam serves as a water trap off of the back of the A/C evaporator. It's purpose is to catch the droplets of condensed water that are blown off of the the evaporator fins and deliver that water to the foam tray / drain at the base of the evaporator. This drain leads to the L shaped rubber hose in the engine compartment, below the reciever / dryer.

Over the years it gets brittle, breaks apart, and gets blown out the dash vents. What this means is that from that point forward the A/C system will not do as good a job of removing humidity from the air in the car. The water droplets will land in the main AC / heat mixing chamber and will most likely get evaporated back into the rushing air or blown out of a duct. I cut a small section of the lip on the foam drainage tray on the off chance that some water might be able to then find it's way out the drain hose but I kind of doubt it would under the full fan load, but it might under lower fan speeds.

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