Air Conditioning Cooling Coil or Evaporator Coil Cleaning Methods
     

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Question: When cleaning a cooling coil do you blow air or water from inside or outside the unit?

Do you blow the pressure air or pressure water from the inside out or from the outside in on the unit? I sprayed it from the outside in I think It may have been the wrong direction. - Sherry 6/7/11

Reply:

If you are trying to clean a dirt-clogged A/C coil, the best result is achieved if you can blow from the clean side so that you are pushing the dirt and debris back off instead of forcing it in between the coil fins. However sometimes it is so difficult to access the clean or outlet side of the cooling coil that technicians use cleaning foams and water instead. In that case they may spray from the most accessible side.

Ultimately, if you can see that the spaces between the coil fins is free of dirt and debris, and you've cleaned the crud out of the housing, and you haven't soaked and shorted electrical components, you've been successful at cleaning the air conditioner coil.

Question: Don't confuse a dirt-blocked coil from ice or frost formation on cooling coils

I cleaned the outside unit by removing the panel and the fan which was attached to some wires. I didn't disconnect or damage anything. I collected 1/4 a garbage bag with the dirt and debris found to the bottom. In attempting to clean the inside unit and fan, I noticed lots of ice on a grid like thingy and some tubes or lines. The inside however looks to be pretty clean but I will wipe it down anyways. I purchased this house in 2006 and so far had to change the compositor battery looking thingy professionally. 2 years ago but still have freezing when it is about 100 degrees outside or more. What else could I do? How do I know if I need freon or refrigerant and where does it goes? Please help ...thank you! - Pamela 6/10/11

Reply:

Pamela it sounds as if you are describing frost and ice formation on the cooling coil (evaporator coil) inside the indoor air handler unit.

Icing coils are caused by low air flow (dirty cooling coil, dirty air filter or duct defects) or by a low refrigerant charge. Adding freon is something that needs a service call from a trained HVAC technician - it's not something a homeowner can or should try to do.

While ice or frost on on the coil could be caused by a dirty coil, the technician needs to defrost the system and inspect the coil as part of diagnosing and fixing the trouble. If on defrost (just leave the system turned off for an hour or so) shows that the evaporator coil is actually clean, then the problem is elsewhere in the system and you'll want to see the diagnostic advice at FROST BUILD-UP on AIR CONDITIONER COILS.

Question: Can chemicals or cleaning products damage a cooling coil in an air conditioner or heat pump?

I recently had some problems with the AC unit. At one point the tech cleaned the coils and etc. and I remember him saying that he used some kind of coil cleaner. After this was done, I started having a major problem of toxic or exhaust like fumes coming through the ducts. I had to turn the unit off because it started burning my eyes, skin and throat. The techs have checked several times and can find nothing wrong.

I read above where it says "Chemical reactions between some coil cleaning products and the aluminum or copper A/C or heat pump coil parts can also produce obnoxious odors or fumes, possibly toxic or irritating fumes, and in some cases may leave an odor in the system that itself becomes an issue". My question is, If this is the problem, what needs to be done to get rid of the fumes and clear out my system? Any help is appreciated. Thanks. - M.B. 6/20/11

Reply:

MB: there are more benign foaming cleaning agents that should not corrode or otherwise damage a cooling coil when used according to directions. If your technician has already used a caustic agent (which is what your question indicates) it may be necessary to further clean the coil and air handler with a non-caustic cleaner to neutralize any ongoing corrosion and to stop generating the odors and fumes you described.

If the service technicians are sure that the odors and irritants you describe are not due to the cooling coil cleaning procedure then it's appropriate to perform some further diagnosis, perhaps by technicians with more experience. That procedure should address the question "Why did the fumes begin only after the coil was cleaned?"

Reader follow-up:

I used vinegar. It has an low acid base, yet it produces some results to smell. I also come back with baking soda to off set any acid. I heard where it was good for drains so I tried it. I like the garden sprayer idea, may use it next time. I used a spray bottle this time and it worked fair. I vacuumed with a shop vac and it still was as clean as I wanted but over time, maybe.

Reply:

Indeed further coil cleaning with a more gentle cleaner to remove left-over chemicals from the coil cleaning job may help; take a further look at the coil fins for damage.

Question: using WEB coil cleaner containing 2-butoxyethanol and diethylene glycol to clean frozen A/C coils

Is it safe to use WEB Coil Cleaner on the Heat Coil (inside)? It contains 2-butoxyethanol and diethylene glycol. The heat pump cooling coils are frozen. I already cleaned the condensate drain pipes.

Reply:

Anon, if your coil(s) are frosting or frozen, the cleaner is not designed to remove ice; you'll need to turn off the system, let the ice melt, inspect the coils for dirt and debris or other damage, and clean them if that's the case. It's odd to have simultaneous icing on both condensing and cooling coils; has anyone checked the refrigerant charge level?

Question: using Simple Green to clean a cooling coil or evaporator A-coil in an air conditioner

Question: I want to clean my evaporator coil,(A-Coil) inside the air handler, with Simple Green and tap water. I'm concerned about the water washing down into unit and damaging the blower motor and electronics. I know there is a narrow drip pan around the base of the coil but i'm afraid of the overflow. Are my fears unfounded or.? - Paul - 10/19/11

Reply:

Cleaning with simple Green or even plain water will risk damage to the blower motor and electronics if you get them wet - they are not intended to be immersed nor soaked in liquid. You should be able to keep water and cleaner on the coil and fins and in the condensate pan. If you do so and there is trivial overspray onto the motor just wipe it off. If you can't clean in the air handler without spraying more water about then you'll want to use taped up plastic to protect electrical components from the spraying procedure.

Question:

My air conditioner coils and fins are still freezing or icing up after cleaning them with water ...could there be something else wrong that it still freeze or ice up? I have to turn on and off the A/C 's thermostat every 15 minutes or so just to melt the ice and for it to cool up again. anything else i can do to fix this problem? - Jack 10/20/11

Reply:

Jack,

if the A/C or heat pump cooling coil is clean and air is flowing across it but it's icing, then I suspect that there has been either a loss of refrigerant (low refrigerant can cause icing at low charge until there is simply too little refrigerant left in the system, then no icing and no cooling)OR there is a problem with the refrigerant metering device such as a sticking thermostatic expansion valve. Either of those diagnoses and repairs will need a service call from a trained HVAC tech. Keep us posted - what you learn will help other readers.

Question: Is using an evaporator coil cleaner regulated by environmental discharge regulations?

During a recent audit finding, and regarding our regular and routine coil cleaning, we were told it is a code violation if you discharge any pollutant or cause, permit, or allow a discharge of any pollutant from a point source without a permit. I don't think this is true or even applicable to coil cleaning...your input is greatly appreciated. 10/18/11

Reply:

Frank, that's a new one on me. Who defined HVAC coil cleaning as a polluting process? If you used soap and water would that be a pollutant? Typically coil cleaners are a foaming agent that is used to help lift dirt off of coil fins. The material is water soluble. If you give us the name of the coil cleaning product you or your HVAC tech intends to use we can further research this question by taking a look at the MSDS for that cleaner. That ought to put an end to what sounds like a bit of an odd question. Finally, I suspect that someone might have been worried that you were going to dump refrigerant into the environment. If that's the case then s/he does not understand that HVAC coil cleaning is an external cleaning procedure that does not address the interior of the HVAC refrigerant piping system.

Question:

Usually, how often should you acid wash the inside air conditioning coils? Please don't tell me when they're dirty.... THANK YOU - Terry 5/6/12

Reply:

Terry: well "when the coils are dirty" is nevertheless the right answer, sort-of.

Really you want your service technician to inspect visually for the presence of enough dust and crud that air passage through (between) the fins has become partly blocked.

Light dusting on the cooling coils is not worth a wash.

Watch out: And we want to "acid wash" coils as seldom as possible because you are using a corrosive material. I'd look into less corrosive cleaning methods.

Question: cooling coils on HVACR equipment in a cement company environment

What should be the recommended fin material and fpi for condenser coils in cement company enviroment?

Reply:

Matthew,
to specify a cooling coil fin material you'd want to list the corrosive ingredients you expect to be in the air. Caustic dust is one possibility but there may be others. With that information I'd call the HVAC manufacturer to ask their advice. I suspect you're looking at a lower heat transfer rate and using stainless steel, or going with a conventional coil and water-washing the outside unit.

Question: Can a dirty cooling coil cause HVAC system vibration? Also the service policy & warranty I purchased is not being honored by the service company.

I have a question concerning the A/C unit. When the A/C Unit turned on (inside furnace located in hallway) had a noise (vibration on the A/C Unit) I have a warranty plan and they send a technician.

Technician checked the blower by sliding the blower from its position and stated blower was OK. Technician went on and check Other parts of the furnace and was unable to determined what was causing the vibration. He had a device (camera) to check inside air handler and notice that the coils were dirty. He stated that it is possible that dirty coils (A/C Unit still operating OK) could cause the vibration on the unit. Technician stated that A/C unit must be pulled/removed from its location in order to clean the Coils, which would cost over $1000.00 to include cleaning coils plus the labor.

Unfortunately the Warranty plan does not cover cleaning the Coils (maintenance), the Warranty Company interpretation of dirty coils is "Clogged coils", which technician stated coils were not clogged just dirty.

My question is: Could dirty coils (unit still cooling & running OK) can cause the vibration? R.V. 5/11/12

Reply:

The assertion that a dirty coil caused the unit to vibrate leaves me baffled. How did the tech explain that?

Indeed if the coil is really dirty and blocked it may frost over or fail to pass enough air and your cooling air will be reduced, but that's not vibration.

Look for loose parts that move when motors or fans run, including a bad blower fan bearing, mounts, loose duct work, etc. Try pressing gently on components to see if the vibration stops - DO NOT GET YOUR FINGERS CUT OFF IN MOVING PARTS - so you may want to have a more qualified tech take a look.

Reader Follow-Up:

Thank so much for your response. As I mention on my email below that the Warranty plan does not cover cleaning the Coils (maintenance), and their interpretation of the technician report that vibration is because of dirty
(clogged) coils. I complained to the Customer Service Rep that the technician DID NOT correct the vibration problem and was not sure what Was causing it. Customer Service Rep suggested to contact the technician and re-submit a report on what could be causing the vibration.

I did contacted the technician, and explained to him that Customer Service denied the claim because of his report stating that the coils were 100% dirty. The technician contacted Customer Service but the claim was still denied based on this report.

As I stated to customer Service and the technician that the Vibration was not FIXED, I still have to PAY $75 Deductable (service Fee) and the vibration problem was not fixed.

My conclusion is that the technician stop searching to determined what was causing the vibration after he saw that the coils needed to be clean and stated that could cause the vibration and he stated that it should be cover under the warranty (technician estimate cost for cleaning the coils $850.00 submitted on his report).

Again, I mention to the technician that he did not fix the vibration problem. I did read the Warranty Plan and it states that cleaning of the coils is not cover under the plan, but my point was to customer service and technician that the vibration problem was not fix. Again, thank you for your response. 5/31/12

Reply:

You can inform the customer service people that a dirty coil blocks airflow but does not cause vibration in the system. I would ask that a more qualified, experienced tech be sent to the job. It sounds from your description as if the tech you had knew that he could blame an excluded item and thus escape honoring the warranty.

Reader Follow-Up:

I agree. When I spoke to the Customer Service Rep, I clearing stated that the A/C Unit was working Ok and the technician verify that A/C air flow/cooling was working ok.

Bottom line is that Customer Service Rep concluded (their interpretation based on report) that warranty plan does not cover dirty coils, and totally ignored the vibration problem.

Do you have an idea about how much (an estimate) it would cost to get the coils clean? I as mention on my previous

Email that the technician estimated about $850 (to include 4 labor hours), he claimed that the entire unit must

be remove and remove all panels in order to the clean the coils, and if it took more than 4 hours, it could cost

more around $1000 to complete the job. I told him he was just cleaning coils not replacing the coils.

Reply:

I would not touch the coils before seeing myself that they are actually dirty and blocked with debris. This whole transaction sounds suspicious. I'd like to see some well-lit sharp focus photos of the cooling coil. Also, when the time comes to clean the coils, there are procedures for cleaning in place.

Reader Follow-Up:

The technician had a device (about two feet flexible tube with camera at the
end) that he insert inside the area where the coils are located, where it shows the coils were dirty. I am sure the coils in any A/C unit after Long period time (5 to 7 years) could get.

I know for a fact that during a semi/annual A/C checkup or Service the technician don't inspect the coils, they just conduct an external checkup.

I agree with you that the whole transaction sounds suspicious to me also.
The company(where technician work for) make a quick $75 and Warranty Plan did not have pay for it.

Reply:

It's a disturbing topic - too often in the news we read reports of companies that sell insurance but who pull out all the stops to resist actually paying on a claim. As you describe no ready access to the cooling coil, cleaning would require cutting and making a (reusable) access cover for an appropriate side of the unit; there are procedures for cleaning the coil in place that should be much less costly. If you choose that approach take some photos and send them along and we may be able to offer other comment.

Please keep me posted on how things progress, and send along photos if you can. Such added details can help us understand what's happening and often permit some useful further comment. What we both learn may help me help someone else. - Ed. 6/2/12

Question: can a bad fan capacitor cause cooling coil frosting?

A tech replaced the dual run capacator on the outside unit of my heat pump system. The fan would not spin and he needed help over the phone to get the unit running again. Could an improper installation of the dual run capacator cause frost and icing? Previous to his visit I never had a problem with frost or icing. - Mike 5/24/12

Reply:

Mike, maybe in some way I don't fully understand. The fan on the outdoor comprressor/condenser cools the outdoor half of the system and thus permits condensing high pressure high temperature refrigerant back to a liquid form. One would think that if the refrigerant didn't condense back to a gas it would not be properly metered into the indoor cooling coil and I'd guess that the result would be reduced cooling, not more cooling.

Usually an iced coil results from
- slower air flow across the indoor coil because of a dirty air filter or fan unit or an indoor blower fan that is not working properly
- a problem with the refrigerant metering device (TEV)
- low but not zero refrigerant in the system

In the link at Related Topics under COOLING COIL see the article FROST BUILD-UP on AIR CONDITIONER COILS where we list other causes of coil frosting such as a dirty air filter or lost air movement capacity due to dirt build-up on the air handler's blower fan blades.

Let us know what your tech finds - it will assist other readers

Question: What's the best way to clean the A-coil without removing it from the air handler?

Would like to know the best way to clean the A-coil without having to remove it fron the air handler. I want to use a foam spray that does not need to be rinsed out, are these types of foams o.k. for the coil? - Mark 6/22/12

Reply:

Mark, some of the foaming A/C coil cleaner sprays are intended to clean the coil fins, drip into the tray below and exit at the condensate drain, some without rinsing. But I'd watch for sending blobs of crud that, if it does not fully dissolve, such as clots of lint and dust, may clog the condensate drain. If you can get good view access to the whole assembly you can be confident of the result.

Question: Water leaks out of air handler traced to dirty cooling coil?

thank you for your detail explanation. I had water beneath the coils on the concrete. The Tech said it was coming from the condensate drain line. It wasn't wet ! I cleaned the water up and stuck my head inside the handler and the water was dripping from the inlet side of the coils. I read where this condition was from dirty coils. I used your article to clean the coils and just a few droplet of condensate remain. I'm going to clean them a 2nd time but I have to rest my back. Thanks for your article that so comprehensible

Reply:

David thanks so much for the feedback.

It makes sense that reduced airflow through a cooling coil might in some arrangements reduce the push through of condensate to the coil inner face where it has an easier time dripping into the condensate tray.

But if you can, send me a photo of what you see of the condensate tray beneath the inlet side of the system coil.

Because the air handler's condensate collection tray ought to extend far enough on all sides of the cooling coil to catch condensate on the front end or inlet side too.

When there are condensate leaks below or out of an air handler and the condensate drain is not clogged, it makes sense to also check too for a tipped or leaky condensate pan.

...

• Thanks to Ato Guy Benfante, Chesapeake, VA 8/26/07 for the photograph of an ice-blocked air conditioning system evaporator coil and for his suggestion that we provide an air conditioning system troubleshooting FAQ.
• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
• John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net
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• Wikipedia provided background information about the definition of HEPA and airborne particle interception.
• Thanks to reader Charles A. Plinton, Norristown, PA, for discussing A/C compressor noise, coil cleaning, and system maintenance - August 2010
• Thanks to reader Nichalus-Michael for discussing use of hydrogen peroxide to clean an HVAC coil, October, 2010.
• C-Shine, Industrial Compressor Component, Mr. Vilas, 706, Atharva Society, Hawa Hira Park, Kurar Village, Near Zam Zam Bakery, Malad East Mumbai, Maharashtra - 400 097, India, Email : icc2006@rediffmail.com, kvilas.icc@gmail.com Telephone : +(91)-(22)-40214595 Mobile : +(91)-9819821666/ 9320520201 Fax : +(91)-(22)-28769485. Web search 10/27/2010, http://www.industrialcompressorcomponent.com/
• CoilShine, described by Goodway, a provider of HVAC coil cleaning equipment and solutions. Tel: 800-333-7467, web search 10/27/2010, http://www.goodway.com/coilpro_chemicals.aspx

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

• Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
  Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
  
• Complete List of Air Conditioning & Heat Pump Design, Inspection, Repair Books at the InspectAPedia Bookstore.
• Modern Refrigeration and Air Conditioning, A. D. Althouse, C.H. Turnquist, A. Bracciano, Goodheart-Willcox Co., 1982
• Principles of Refrigeration, R. Warren Marsh, C. Thomas Olivo, Delmar Publishers, 1979
• "Air Conditioning & Refrigeration I & II", BOCES Education, Warren Hilliard (instructor), Poughkeepsie, New York, May - July 1982, [classroom notes from air conditioning and refrigeration maintenance and repair course attended by the website author]
• Refrigeration and Air Conditioning Technology, 5th Ed., William C. Whitman, William M. Johnson, John Tomczyk, Cengage Learning, 2005, ISBN 1401837654, 9781401837655 1324 pages
• Air Conditioning SEER - New DOE Air Conditioner and Heat Pump Efficiency Standard
• Asbestos HVAC Ducts and Flues field identification photos and guide
• Fiberglass: Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation