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1997 SLS
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550 Posts
Discussion Starter #1
My question is how to properly clean out mold developing on the evap coil fins that can produce a bad odor in the A/C system. I saw a morning show on this a few years ago, but they didn’t go into how someone could do it for themselves. Basically, a “shop” drilled 2 holes (probably 7/16 inch) in the top of the evap coil housing and then with a special wand, injected or sprayed a substance across the coils and fins to remove any mold or dirt that would collect on them. I would assume that the substance would just drain out of the bleed hole at the bottom of the case. Then most likely, plastic press-in tabs would be used seal the drill holes.
Has anyone done this and could you describe exactly where the access holes should be drilled for a Seville? My concern is hitting fins or coils close to the housing with a drill. Also, would a mild solution of bleach and water do the trick? Is there something off the shelf at an automotive store, such as a kit, available? (I haven’t seen anything like this). I’ve done the old Lysol sprayed in the cowl vents with the AC on, but that only works for a short time and I doubt that gets into all the fins to clean them. Here are some interesting links on the subject:
http://findarticles.com/p/articles/mi_m0820/is_1999_June/ai_54668649
http://www.imcool.com/articles/aircondition/evap_stinks.php
 

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2004 CTS-V
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40 Posts
Not sure about how to access the coils, I'll leave that to someone else but I can help with the other part. I have an air duct cleaning company and when we clean coils in residential systems (the car is the exact same thing but smaller coils) we use an alkiline based cleaner. Most home improvement stores will carry a few of the products. Just make sure you use alkiline base and not acid based. Some of these product will come in an aerosol can which might make it easier. you will apply it to the coils and let it sit for a few minutes then rinse with water.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,994 Posts
You'll never get rid of that Lysol smell. Is there an outline on top of the HVAC box with CUT HERE TO SERVICE embossed in it? If so, cut that out to clean it.
 

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Sedan de Ville, CTS
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4,764 Posts
Dip car in alkaline based solution. (Lincoln used to dip entire cars in rust proofing in the mid-60s. Their marketing pictures showed cars being immersed.)
 

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1997 SLS
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550 Posts
Discussion Starter #5
Thanks to all for the suggestions...I will look for an alkaline cleaning solution.
Ranger, thanks for the tip on that cut out...I found it on an area between the blower motor and where the feed/return tubes go into the evap chamber. But this raises another question: it's an odd shape so once it's cut out, how do I plug it again? Does GM sell a plug that fits it? Or could I cut circles in there and find round plugs say at an Ace hardware to close it after the cleaning. Here's another question: Am I puncturing an area just above the evap coils? would a sprayer applied in that area with alkaline solution do the job? If anyone has a shop manual showing details of the evap coil fins in relation to the case - that would be ideal. Thanks in advance.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,994 Posts
Yes, I believe that cut out panel is above the evaporator. Once it is open you should be able to clean it with a tooth brush or something similar and flush it clean water. Patch it with duct tape, aluminum tape, flattened beer can & RTV, save the cutout and tape it back on. There are a multitude of ways to patch it.
 

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'98 STS (RIP @ 206,xxx miles)
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4,854 Posts
As a final step, enable the "afterblow" function if that is an option with your model/year.

I do like the beer can recycling idea :alchi:
 

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68 DVC, 96 FLTWD Brgm, 11 CTS Premium (two)
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1,623 Posts
Yes, I believe that cut out panel is above the evaporator. Once it is open you should be able to clean it with a tooth brush or something similar and flush it clean water. Patch it with duct tape, aluminum tape, flattened beer can & RTV, save the cutout and tape it back on. There are a multitude of ways to patch it.
I was going to suggest duct tape but you beat me to it.

You can also try vacuuming first to remove some particulates before brushing / washing.
 

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1997 SLS
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550 Posts
Discussion Starter #9
Thanks to all who suggested things. I'm going to seek out the alkaline cleaner and check with my dealer for a proper plug for the access cut-out. I have a feeling this could be a yearly maintenance. Once I finish the job, I will post steps with pictures on Tech Tips.
Mike: I like the idea of using a wet-dry shop vac on the access - and maybe it would work to help suck out the flushing process thru the weep hole under the car too. Will let you know how it goes.
 

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1997 SLS
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550 Posts
Discussion Starter #10
OK - I finally did this maintenance after getting the run around from 3 dealers on the cover plate. It did work though - and if anyone is interested in the process, I will post it here. It's in a format that could go to tech tips if a moderators warrants it's worthy!
Thanks again to all who pointed me in the right direction - I think this will now be an annual task for me.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,129 Posts
Google something like "cadillac forums hvac evaporator cleaning" or something close - always preceded by "cadillac forums .......". There have been other threads on this, and the process - and the spray used - is discussed in the GM service manuals for our various cars.

If the Google search doesn't turn up anything, a page by page search of Tech Tips might get you somewhere.

Service manuals from eBay or www.helminc.com. For instant gratification, look at www.alldatadiy.com.
 
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