Air Conditioner Blowing Flakes Of Greenish/black Patches From Ducts

[sundancev]

Hello all. We live full time in our 39' Fleetwood Providence. We have two roof air conditioners that have and continue to operate well in terms of cooling efficently in very hot dry climates as well as hot and humid south Florida climes. Recently we have noticed flakes of some sort of substance coming from our roof air conditioner ducts. I sort of think it might be some sort of algae or similar substance. Problem has developed since we left South Florida and moved into West Texas to Southern California. Makes one think if it is algae of some kind it is perhaps dying in the much dryer environment we presently are traveling. Has anyone else run into such a thing and know of a cure. It sort of makes a mess if it lands on clothes/linens etc. Cleans up fine from tile floors. Sometimes can get a bunch in one day and none for a couple of days. We are aware of the recommendations of numerous folks smarter than us that moisture in a motor home environment is a big problem and as such contributes to growth of mildew etc. The air conditioners due function extremely well other than this recent issue. Many thanks in advance.

G Paul Whorton

2004 39' Fleetwood Providence, Four Slides, 350 HP Cummins, 7.5KW Onan towing Honda CRV

[wolfe10]

Sounds like you need to clean the A/C EVAPORATORS. If you are safe working on the roof, buy some commercial A/C evaporator cleaner (same as would be used in a stick home) and clean them. Does require some disassembly, as you need to remove the A/C shroud and then the cover over the evaporator.

Not an uncommon problem in humid area to grow quite a collection of mold, mildew and bacteria.

[danddferr]

Another area to check is the duct work in the RV. Pull off a couple of your Ac vents and look at the inside of your ducts. Might have some mold growing in there. Cleaning that out will be difficult but necessary for your health. A plumbers snake with a white t-shirt attached to the end might tell you if you have mold in the system.Good Luck .

Dan

[sundancev]

Brett: I took off AC cover and shroud that covers evaporator (radiator looking object.) Evaporator does not look to bad as far as dirt, however I could see a limited amount of the inside of the squirrel fan and it's blades appear to be covered with Mildew. I downloaded copy of service maunal (RVP8000) and they recommend removal from roof to clean Evaporator Assembly. That is not a good option for us and wonder if you or any other reader may have a suggestion as to some type solution perhaps bleach that could be sprayed a little at a time then spin the blade, spray a little more etc until we get some degree of coverage. We are now in San Francisco with our travels and I am hopeful of finding an AC company to purchase commercial evaporator cleaner you referred too. I gathered from your previous reply the use of evaporator cleaner would not require removal of AC from roof. Many thanks. Paul

[wolfe10]

I would get a commercial evaporator cleaner at any home HVAC store and many box stores. Yes, you have to use work towels or something to insure that the cleaner does not get down into the air return or air ducts, but in many cases, the A/C does not need to come off the roof.

Be sure you are looking at the EVAPORATOR, not the condenser (which you can see without removing the shroud. The evaporator on a home system is the part in your home. The condenser is the part outside. Compressed air of water (carefully) can be used to clean the condenser, it does not drain into the interior unless you really flood it.

[sundancev]

Brett: Do you have a suggestion for the squirrel box fan (mold). I think that is where most of the black stuff is coming from. Should I try to spray some bleach (I can only get to a little portion at a time.)

[wolfe10]

I would use commercial evaporator cleaner. Bleach is really rough on aluminum-- and a lot of the A/C is aluminum.

[sundancev]

OK Brett I appreciate your help. We are in San Francisco this week and talked to AC contractor. He did not have small quantities of Evaporator Cleaner and suggested his wholesale suppliers would not sell us any. He suggested OReilly auto parts locally where we obtained a 4 oz aerosol can of something called "A/C and Heater Duct Cleaner". This product instructions indicates it can also be used to clean evaporator, but appears to be sold primarily for use in auto A/C with suggested us to be spray in intake side of AC vent. The squirrel box fan we referred to actually has plastic blades, but we will go with your suggestion to stay away from bleach. Paul

[wolfe10]

Paul,

With plastic blades, if (ya, big IF) you can get to the blades as you rotate the fan, you might try some cleaner on a thin rag, using a Popsicle stick to get it in between the blades. Please tell spouse it WILL take a dozen Popsicle to get the job done-- blame me if you wish. Might as well get something for your hard work.

[cobrafang61]

Yes the coils need to be chemically cleaned with coil cleaner, 409 or similar things are only better than nothing, . Coil cleaners available at HVAC/R supply houses, is a liquid that foams once its sprayed into the coils and foams, pushing the debris and film out.

Its a mild acid and strips the smoke, dirt, dust, muck away like new allowing for a tremendous improvement in heat transfer! We are talking a 20 degree differential typically at best, now remove 2-3 degrees from that and its bad. Getting to both sides of each coil is important, but the side that's exposed to the incoming air gets dirtiest.

Insure you get the foaming type, "coil brightener" type, non friendly type in other words, the safe stuff can be ingested without too much issue. I wouldn't try that with this stuff, in fact wear playtex gloves as it burns your skin after a few minutes! It smokes and foams the coils clean, use a garden type pressure sprayer that adjusts to a stream, to fog it will not penetrate the fins & rows of coils depth, shoot it into the coil between the pipes if you can see them to penetrate best, methodically spray each row quickly as it will begin foaming and require a good rinse too. Cover any controls or motors etc. so they don't get wet.

It's about 15 bucks for a gallon of coil cleaner and works wonders on other things too. I had a friend selling a old beat up ford truck that was white with dirty greasy stains and etc, I tried a spot with the cleaner and did the truck it was a new truck in appearance! It ate the old paint off! lol!