Industrial Grade A/C Drain Leak Fix Instructions -

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post #1 of 6 Old 08-18-2007, 12:03 PM Thread Starter
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1997 ZJ 
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Industrial Grade A/C Drain Leak Fix Instructions

Permanent AC leak Fix – 1997 Jeep Grand Cherokee - Bypass the stock drain!

Pictures here:

Wet passenger side carpets? Blower motor controller or blower motor going out? You must drain the condensation out of your HVAC unit properly or your evaporator core will rust out and fail plus you can damage your controller and fry the blower motor. Then it’s $800-$1,000 just to replace the evap core way under the dash.

Below are detailed instructions and a parts list for a permanent industrial grade (though very easy) fix to this problem. The stock drain will endlessly clog so a better fix is in order.

Parts list: (all except RTV bought at Home Depot) (Total Cost approx $10.00-$15.00)
- Two to three feet of Clear Vinyl Tubing – (WATTS tag says ¾” x ½”) (Fits snugly on the nipple fittings below)
- Two A-740 Brass Pipe Nipple (1/4” MIP x Close) Copper threaded fitting
- One A-739 Street Elbow (1/4” MIP x 1/4” FIP) Copper Elbow Fitting
- RTV Sealant

Tools list:

- Drill with 3/8” drill bit
- Dremel tool with cutting bit or a nice round metal file
- Pliers


- Pull back the soggy carpet in the passenger side foot well.
- Locate the bottom of the black HVAC unit inside the passenger side foot well.
- Find the protruding round drain section that hangs down into the foot well against the firewall.
- Locate the black circle area and drill a big 3/8” hole right in the center. (Have a bucket ready if you're all clogged up. Mine had a 1/2 gallon of water pour out.)
- Stick an Allen wrench/coat hanger in there and clear out the drain.
- Enlarge the hole a little using the Dremel tool or round file until you can just screw the Brass pipe nipple into the hole half way.
- Screw the Brass Nipple into the Street Elbow all the way and tighten with pliers.
- Place lots of RTV sealant around where the two fittings meet then screw the nipple end tightly into the new hole. Position the elbow so it faces right and down a little.

- Remove the small right kick plate/fuse cover, unscrew the lower trim panel and pull away. (Not necessary to take it all the way off)
- Unscrew the black wiring cover along the floor’s edge and move out of the way.
- Feel under the car right there and find the cross member that goes side to side.
- Drill as 3/8” hole behind that area and over a few inches. The black wiring cover should allow lots of room for the hose when you replace it.

- Enlarge the hole a little with the Dremel tool or round file so you can just screw the Brass pipe nipple into the hole half way.
- Screw in the Pipe nipple half way down (to where the threads stop in the middle) and put RTV sealant all around where it meets the metal. Place RTV on the underside as well around the fitting.
- Shove one end of the vinyl tube on, ensure a good seal then replace the black wiring cover and trim panels. Snake the tube up and to the left towards the hole in the HVAC unit.
- Size the hose up to the new fitting in the AC drain and cut. Connect hose and replace carpet etc.


1.) Watch the tube to make sure it is draining. If there is a clog, just pop the tube off and clear it out or blow it out with compressed air.
2.) You should be fine when mudding or driving in high water though you may want to plug up the hole in the bottom of your jeep with a rubber stopper. Just remember to remove it when done.
3.) For even more protection, scrape around the black round drain in the HVAC unit where it meets the firewall, replace any foam with RTV sealant and apply generously all around the area.
4.) Worried about looks? Spray paint the fittings and hose flat black... no one will ever know.

No more soggy feet!

Last edited by sixpackFL; 08-21-2007 at 09:46 PM.
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post #2 of 6 Old 08-18-2007, 12:39 PM
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Nice job 6-pak

Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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post #3 of 6 Old 09-14-2007, 01:57 PM Thread Starter
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ttt ttt ttt
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post #4 of 6 Old 07-22-2008, 01:34 PM
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thanks a ton man....i did this in my 97 zj and it works pefect!
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post #5 of 6 Old 07-05-2013, 06:16 PM
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How easy is it to get the black drain/housing plastic part out? I am getting the floor flood, and took the carpet back to have a look and it seems someone already tried to repair it because it is cracked all the way around the black round drain part in the pictures, where it connects to the evaporator? housing piece. Like a passenger stepped on that round area really hard, cracking it where it meets the square housing. The seal from the "repair" is coming loose, and I am getting the flood. I can get pics if you want to see...but how easy is it to change out this plastic housing piece? Is it just what I can see, or does the piece extend up into the dash, making it difficult to remove?

Are the any existing pictures of this part being removed, so I can get my bearings? I don't want to get into it, maybe damage it, and then realize it is impossible...without checking with you guys.
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post #6 of 6 Old 05-20-2014, 12:38 PM
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You have to remove the entire evap box if you want to do that, which will be a total pain.

Best option is to try this:

As well as the fix in this thread.

You might have to seal that sucker up with hard silicon as well, if it's cracked. Basically you want a tight seal at the bottom of the evap chamber leading to wherever it's draining. (This is probably the most obnoxious ZJ problem of all time.)
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