Air conditioner or heat pump cooling coil / evaporator coil cleaning methods:

These same methods will work on the outdoor coil or condensing coil as well.

Our photo at page top shows a very dirty cooling coil in the attic air handler component of a central air conditioning system.

• How to clean a dirty or moldy air conditioning cooling coil or evaporator coil, or a dirty condensing coil
• Use of spray foam cleaners & deodorizers on cooling coils
• Use of liquid cleaners on cooling coils
• Use of compressed air to clean cooling or condensing coils
• Use of pressure washers or steam to clean HVAC coils

Procedure for Cleaning Air Conditioner or Heat Pump Evaporator Coils

An HVAC coil is a set of finned copper tubing that is used to transfer heat: cooling or warming air as required by the movement of air across and through the coil surfaces.

It's normal for airborne dust and debris to collect on and ultimately begin to block air movement through the HVAC coil. Blocked air flow reduces the ability of the system to cool or warm air and can lead to even more serious operating problems, so periodically these coils must be inspected and cleaned.

Thorough cooling coil or A/C evaporator coil cleaning can require cutting refrigerant lines, removal of the coil and other components for cleaning, and re-installation, pulling a vacuum on the refrigerant lines, and recharge with refrigerant.

Such service and repair may involve significant expense. For this reason, there are several "in place" cleaning methods using foams and sprays that are a simpler procedure for cleaning an air conditioning or heat pump coil.

Watch out: Choosing the wrong type or wrong chemistry of coil cleaner or failure to rinse off cleaners (some require rinsing) can result in costly damage to the coil and could even be unsafe. A quick read through the HVAC coil cleaning approaches given here will let you choose and use an appropriate method.

Article Contents

• BASIC CONCEPTS of HVAC COIL CLEANING
• AIR to CLEAN the COIL - Use compressed air?
• BRUSH CLEANING of COIL SURFACES
• CHEMICAL COIL CLEANERS including "self-rinsing" sprays and foams
• DETERGENTS for CLEANING an HVAC COIL
• DO IT YOURSELF HOME MADE COIL CLEANERS?
• PRESSURE WASHER for COIL CLEANING
• STEAM CLEANING HVAC COILS
• CORROSION at COILS DUE TO CLEANING? - field report
• HYDROGEN PEROXIDE COIL CLEANER? - field report
• WHERE TO BUY HVAC COIL CLEANING PRODUCTS - brands, choices, manufacturers

Watch out: be sure that electrical power is off to the HVAC equipment before opening access panels or working on the system. Relying only on the door safety interlock switch to turn off equipment power may be unsafe as wiring inside the unit will still be "live" in some locations.

Watch out: review your choice of HVAC coil cleaner with the equipment manufacturer and/or the cleaner manufacturer before choosing a coil cleaner, and then be sure to follow the coil cleaner's instructions.

...

Basics: How & Why Air Conditioning & Heat Pump Evaporator Coils (Cooling Coils) are Cleaned

Which Cooling or Heat Pump "Coil" is Which: Condensing Coil & Cooling/Evaporator Coils Defined

The COOLING COIL or EVAPORATOR COIL discussed here is the evaporator coil found inside the air handler, used to cool air blown across it and into the building occupied space. If your concern with your equipment is a heat pump, these terms can be a bit confusing because in heating mode, your heat pump system's indoor coil is warming, not cooling the air blown across it.

The CONDENSING COIL is normally on the outdoor or compressor portion of your air conditioning system. The job of the condensing coil is to cool high temperature refrigerant gas to condense it back to a liquid refrigerant form.

Why do we clean the HVAC evaporator or cooling coil, or the condenser coil?

Dirt and debris accumulating on an air conditioner or heat pump coil block airflow across the coil, increasing the cost of heating or cooling the building.

In severe cases, cooling or condensing coils can become so blocked that air flow is seriously reduced, possibly also leading to an evaporator or cooling coil icing problem indoors or an overheated, damaged compressor outdoors, or simply loss of cooling capacity of the system.

In addition, a blocked evaporator coil can cause the HVAC compressor to run at higher than normal temperatures - a condition that over time can break down lubricants circulating inside the system, thus shortening the life of the compressor motor itself.

Air Conditioner Evaporator Coil Blocked by Debris

ICE on the COOLING COIL is not the only (nor even the most common) cause of blocked air flow in an air conditioner.

This photograph shows how easily debris can stick to and clog the inlet side of the cooling coil in an air conditioning system. This evaporator coil was nearly totally blocked with dust and debris. How does this happen?

There was no air filter installed in the system. Ordinary house dust is comprised largely of fabric fibers and skin cells.

These and other debris in building dust, such as soot and organic particles like pollen and mold spores, all join to form a gray mat on the fins of the cooling coil in an air handler.

Debris sticks particularly quickly to this surface because of the combination of close spacing of the cooling fins (about 1/16" apart) and the fact that condensate forming on the coil keeps the surface damp.

Details about the detection and cleaning of dirt and debris which block or clog up an air conditioner cooling coil so much that air flow is blocked are

at DIRTY COOLING COIL / EVAPORATOR COIL.

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Using Air: Compressed Air for cleaning HVAC evaporator coils

Some HVAC technicians clean an evaporator coil by blowing it off with compressed air. This is a quick and probably effective method to clean the coil, which has the additional feature of blowing dust, debris, and possibly mold into the building air - not something we approve.

Air is sprayed from the cleaner side of the coil towards the dirty side - or in other words, in the opposite direction from the normal air flow across the coil. Be sure to spray from the correct side of the coil or you'll just be forcing dirt and debris more deeply into the coil fins.

Watch out:  if you are using high pressure air to try to clean a coil, be sure you blow air at right-angles or straight through the coil fins. Blowing high pressure air (or water or steam) at the HVAC coil fins on an angle is likely to bend over the fins, clogging the coil and possibly ruining it. If just a few fins have been bent on a coil they can often be straightened by working gently with an HVAC coil comb designed for that purpose.

Watch out: if you are not careful, just using compressed air to blow off a coil may leave a large amount of dust and debris inside the air handler where it collects anew on coil surfaces, or in your eyes (dangerous). Using a shop vac in concert with the compressed air sprayer and moving carefully (to avoid damaging coil fins) can reduce dust and debris spillover and make cleaning up easier.

Condenser coil cleaning: We don't have a complaint about using compressed air to clean an outdoor evaporator coil since we don't have the same concern about blowing debris into the building or its duct work.

...

Brush-cleaning of A/C or heat pump cooling or heating coils

When the coil is soiled by a fairly light coating of dust and debris, it can often be successfully cleaned using a soft brush.

If you clean your A/C or heat pump coil every three or four months using this method, you may reduce cooling (or heating) costs and you may be able to avoid more costly or troublesome coil cleaning procedures.

If your HVAC equipment is operating in a dusty area or if no one has been maintaining proper filters in the system, it is likely that you'll need to clean the coil more frequently, perhaps even monthly to keep the A/C or heat pump system at peak operating efficiency and effectiveness.

We have tried using a shop vac with a soft brush attachment to clean the A/C coils, but if your coil is mounted in the air handler so as to not leave much room to access all of its surface, this approach doesn't work well.

Watch out: to avoid damaging coil fins when using any tools, brushes, or vacuum cleaners around the equipment.

OPINION:

Indoors at the air handler and at split system A/C or heat pump units, we like to use a combination of a soft paintbrush or bristle brush combined with a shop vac to clean the cooling coil.

But if the indoor unit is very dirty and appears to be moldy as well, we use a mild disinfectant spray cleaner, perhaps containing dilute bleach both to help clean the surrounding plastic surfaces and to retard future mold growth.

See a detailed example

at SPLIT SYSTEM AC MOLD CONTAMINATION REMOVAL 

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Using Chemicals to clean A/C coils

There are plenty of coil cleaning chemicals sold for cleaning A/C or heat pump systems, both acid and alkaline-based.

Watch out:  We do not recommend using strong chemicals on an A/C or heat pump coil because of the risk of corrosion damage to the coil or the production of noxious odors & fumes. To be safe, check with your HVAC equipment manufacturer to be sure that your cleaning approach is one they approve.

Indeed there are foaming cooling coil cleaners on the market that can gently lift and help remove coil-clogging debris with minimum damage to the cooling coil.

Do not use an acidic soil cleaner on coils made of aluminum, copper, or other metal that may be damaged by the corrosive effects of the acid. Some air handlers use a plastic blower squirrel cage fan wheel that is also sensitive to acids, becoming brittle and possibly breaking from acid treatment.

Some HVAC service companies may use an acidic coil cleaner on the outdoor coil, followed by a water wash.

Some HVAC service technicians, whose comments we've read or asked-for, opine that plain water is perfectly adequate to clean and rinse most residential outdoor coils.

Using a Self-Rinsing coil cleaner

Using Foam or spray HVAC coil and fin cleaners

When using a garden sprayer (or a sprayer that may be included in some prepackaged A/C coil cleaning systems and products), the coils are sprayed with a foaming cleaner specifically designed for HVAC systems. An advantage of this approach is that it is mechanically gentle, reducing the risk of damage to the coil or its fins.

And if you select a benign cleaner, it is also chemically gentle, avoiding corrosion damage to the coil.

Is Coil Cleaner Rinse-off Needed or Not?

Some but not all coil cleaning sprays and foams require rinsing of the coil after use.

Typically the outdoor coil in the compressor/condenser unit will use a coil cleaner that is followed by a rinsing step since rinsing the outdoor equipment can be practical.

Indoor coils in an air handler are usually selected from products that don't require a rinse step since rinsing with a garden hose (for example) would be impractical indoors.

Cleaners that do not require an additional rinse step are typically described on their label or in their instructions as "self rinsing", typically using a slightly alkaline detergent cleanser.

How does a self-rinsing coil cleaner work? Residues from the coil cleaner are washed off of the coil fins and tubing by condensate that forms on those surfaces when the indoor unit is run in cooling mode.

That rinsing condensate is then collected in the coil condensate drip pan, routed from there to an approved condensate drain, or perhaps through a condensate pump to the drain.

(CONDENSATE HANDLING, HVAC has details)

This HVAC coil spray approach has the appeal that the total cleaning cost is low, no rinsing is necessary with some products, and the coil looks nice.

Where does the debris and run-off cleaner go? It should drip into the condensate pan for disposal through the condensate drain system.

The manufacturer says the coil and fin cleaner also removes odors from the system, but if your HVAC system is quite dirty, additional steps will be needed to clean the blower assembly and the ductwork.

After the coil cleaning foam has worked on the coil surfaces and dripped to the condensate pan below, use a wet-dry shop vac to clean up the mess from the pan, followed by careful wiping as we cited above.

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Using Detergents or Water for cleaning A/C coils

Using a simple hand sprayer or garden sprayer (these produce a gentle spray), it may be possible to clean your A/C or heat pump coil effectively using tap water or a mild detergent.

The advantage of using these gentle solutions is that there is little risk of damaging the coil fins or tubing compared with the use of more harsh chemicals.

Wet the A/C or heat pump coil surfaces with your spray-on detergent, let it soak in for 15 minutes or so (but not long enough to dry out), then rinse the coil and coil fins clean. Remove spillover and debris from the condensate pan where your spray and debris land, using a shop vac or hand wiping.

Watch out: don't bang around inside the air handler with your shop vac or you may damage the evaporator/cooling coil or coil fins; and be careful when wiping by hand that you don't get cut on sharp fin edges.

If using water or a non-sudsing mild detergent doesn't work to clean off your coil, you may need to use a more aggressive coil cleaning method such as those described below.

 

...

Do NOT Make Your Own coil cleaner chemical or spray

Do not try making your own coil cleanser out of other household cleaners like bleach, dishwasher or laundry detergent, as these may be harmful to the coil metallic fins or even its tubing.

Do not use a coil cleaner containing trichloroethylene inside buildings (such as schools or post offices) where use of those products is prohibited.

Watch out: we do not recommend use of high pressure cleaning on cooling or condensing coils. High pressure can damage delicate coil fins and can even blow off or damage sensors or electrical connectors.

...

Using Pressure Washers to clean A/C or heat pump coil fins & tubing

Professional HVAC service companies often use a portable A/C coil pressure washer designed for that purpose.

Unlike cleaning detergents or foams, a pressure washer is a physically more aggressive coil cleaning method and is perhaps the most thorough or effective method for cleaning a badly soiled or blocked HVAC evaporator or condenser coil.

A portable pressure washer unit such as Goodway's CC-140 contains both a coil cleaning solution (typically a detergent mix) and a battery-operated pressure sprayer that can deliver as much as 140 psi. Heavier-duty coil cleaning pressure sprayers are available for commercial units and larger, or heavier, wider coils.

Watch out:  as we warned earlier, if you are using high pressure air, water, or steam to try to clean a coil, be sure you blow air at right-angles or straight through the coil fins.

Blowing high pressure air (or water or steam) at the HVAC coil fins on an angle is likely to bend over the coil fins. And don't over-do it and don't spray more cleaner than needed - you'll just have more liquid cleanup to do after the coil has been treated.

...

Using Steam-Cleaning of A/C or heat pump coils

Steam is used by some technicians to clean HVAC coils, in a process similar to that we described above for compressed air.

Watch out:  as we warned earlier, if you are using high pressure air, water, or steam to try to clean a coil, be sure you blow air at right-angles or straight through the coil fins. Blowing high pressure air (or water or steam) at the HVAC coil fins on an angle is likely to bend over the coil fins.

If your air conditioning or heat pump system has lost its cooling capacity or won't start, see REPAIR GUIDE for AIR CONDITIONERS. See COOLING CAPACITY, RATED of air conditioning equipment if the system seems to be working but is inadequate to cool your building.

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Field Report: Corrosion Visible after a cooling coil was cleaned

I just had my duct work and AC cooling fins cleaned out. After the cleaning it appeared as if the aluminum cooling fins were full of with fluffy green stuff.

I called the technicians who came back to look and then explained that what I was seeing was corroded aluminum that was more visible since the cooling fins are now clean. Although this sounds plausible I have two concerns.

1. if it is corroded aluminum do I need to be concerned about using the ducts.

OR

2. it is not corroded aluminum and they did a really bad job at cleaning

The cleaners are part of the national duct cleaners association (NADCA), seemed quite knowledgeable and experienced (no complaints, A+ at BBB), but I am surprised that the fins look so bad. I would like to know whether what I am seeing is to be expected.

I did snap a picture on the one side of the "V" that was easily accessible, here it is. This is the AFTER cleaning picture, I don't have a before. The schmutz has a slightly greenish hue.

The AC handler and ductwork is old, and based on the amount of crud throughout the system appeared as if it may have never been cleaned before (the condenser unit itself is 25+ years old, but still working). That conclusion also comes from the fact that the prior owners seemed to take pride in performing NO basic maintenance on the house for many years. I just hope that firing up the AC system in a couple weeks won't endanger my family. - Kevin 4/28/2014

thanks. K.C. 4/28/2014

Moderator Comments

In my initial reply I said "I am not sure I buy the explanation that "you only see the crud because now we've cleaned the coils". That would be the case if we saw thick green crud that was actually blocking or covering-over the coil assembly.

But now that I can benefit from seeing your photo (above left) I think that we are looking at corroded aluminum fins on the coil and that the cleaning company is being dead honest in saying you couldn't see this before - this condition would have been covered if there were a layer of thick dust and debris.

Your photo is not quite clear on the point, but if there is good air flow between the fins on the coil and presuming it's not leaking, it should be functional.

This is about as good as you're going to get in cleaning this coil. It would not be likely that the coil cleaning procedure using approved methods and materials would endanger your family. (You might however want to inspect the HVAC system ductwork for cleanliness, including the air handler and blower fan assembly.)

There is some heat transfer loss where aluminum coil fins are deteriorated by corrosion, but most likely a significant gain in coil performance overall by cleaning if it was previously debris-clogged.

To understand this coil's performance better, an in-focus photograph looking directly into the coil fins - at right angles to the plane of the coil - would let us see whether or not there is open air space between the fins.

Take care not to damage the fins nor cut yourself on sharp edges. It may help to try shining a light from the other side of the coil if it's accessible. If not the photograph will rely on lighting or a flash from the camera's side.

If we see open air space between the fins then the coil has been opened as successfully as we're going to get it.

Unfortunately I cannot recommend any more aggressive cleaning like brushing. The aluminum fin material is thin to begin with and is more fragile now as it has been corroded. More aggressive cleaning that bends (which means blocks) or removes (which means still more capacity loss) fin material just makes matters worse.

Replace the coil, or the whole unit, if/when the coil leaks refrigerant.

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Field Report: Using Hydrogen Peroxide to clean an HVAC coil?

I used hydrogen peroxide 3% to do the job and it gave a bad smell. Kind of a chemical smell. I think the peroxide reacted with the zinc,aluminum, copper or nickel metal in the cooling coils. Is it OK to use peroxide to clean cooling coils besides the conventional HVAC tech cleaning methods? I live in an apartment and sometimes my AC air starts to get a moldy smell to it.

The first time I cleaned it out myself there was all this orange yucky fungal sludge in the drip tray and there was so much of it that it had clogged the drain pipe which I had to clear out.

I cleaned it out with 5% hydrogen peroxide and whatever it was it bubbled like crazy so I believe the peroxide was reacting with a biological agent. It also reacted with something between the fins of the cooling coil to give a smell slight of sulfur and burned gunpowder. What are your thoughts on the matter? - N.M.

Moderator Comments on Peroxide as an HVAC coil cleaner

While we have read reports that the oxide on the surface of aluminum HVAC coil parts reduces the severity of chemical reaction between an acid or base cleaner and the metal, we have also had reports of problems with corrosion and odors when this approach was tried.

So while the "bubbling" action of hydrogen peroxide is appealing as a cleaner, we are warned that chemical reactions between some coil cleaning products and the aluminum or copper A/C or heat pump coil parts can corrode the fins or tubing, damaging the system, ultimately leading to leaks and the need for a costly coil replacement.

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.

See our discussion of detergents and foam sprays for coil cleaning, above in this article - those are safer approaches to coil cleaning, especially if you're not an expert.

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List of HVAC coil cleaning chemicals, foams, and sprays

Where to Buy HVAC and Refrigeration Equipment Coil Cleaning Products

• AC-Safe Coil Cleaner, Nationwide Products, AC-921 Foam Coil Cleaner
  
  
  SDS for AC-Safe Coil Cleaner [PDF] retrieved from Home Depot Stored 2017/10/23
• C-Shine is a mix of chemicals produced in India and intended to remove dirt, grease, and debris from A/C coils in a process the manufacturer, ICC, describes as "chemical descaling" or (misspelled at their website) chemical descaling
• Coil Shine is described by Goodway as
  
  "a [non-acidic blend of powerful, fast acting detergents, specifically formulated for use with the CC-140 CoilPro power washer] biodegradable, expanding foam detergent specifically formulated for use with the CoilPro.
  
  This is a non-acidic, non-fuming solution that can be safely washed down drains.
  
  CoilShine-BC is a commercial grade, ready-to-use mold inhibitor for HVAC systems that helps prevent the growth of odor, stain and damage causing organisms such as mold, mildew and fungi."
• Com Koil External Condenser Coil & Brightener (Acidic), from ComStar, ComStar International Inc. 20-45 128th Street, College Point, NY 11356 USA Tel: 718-445-7900 800-328-0142 described by the manufacturer as ok for aluminum and brass, rinsed with water
  
  
  ComKoil SDS [PDF] contains hydrofluoric acid, phosphoric acid, surfactant, and water.
• ComStar 90-184 Foaming Coil Cleaner (non-acidic), for both evaporator and condensing coils,
• Nova-Tech International sells a dry powder used to make an alkaline HVAC coil cleaning liquid that can be sprayed onto the coil.
• Nu-Calgon Cal-Brite A/C Condenser & Evaporator Coil Cleaner, a liquid, sold in concentrated form, used to remove lint, dust, grime, oxide deposits, cottonwood, bugs, grease, dirt, oil from a cooling or evaporation coil in HVAC equipment.
  
  Nu-Calgon, 2008 Altom Court St. Louis, MO 63146 (800) 554-5449 Website: http://www.nucalgon.com/
  
  Contains ammonium bifluoride and glycolic acid. See this
  
  Cal-Brite Nu-Calgon MSDS [PDF], retrieved 2017/10/23, original source: http://www.nucalgon.com/assets/MSDS/English/4133.pdf
  
  Nu-Calgon Cal-Brite Coil Cleaner SDS Safety Data Sheet, retrieved 2017/10/23, original source: http://www.nucalgon.com/assets/SDS/English/4133_SDS_ENG.pdf
• Nu-Calgon Nu-Brite A/C Condenser Coil Cleaner, concentrated, water-based with degreaser, this is a foaming cleanser diluted with water 4:1
• Nu-Calgon, Evap-Fresh Coil Cleaner, no rinsing required, Evaporator Cleaner, Liquid, for Evaporator Coils in Small Air Conditioners, HVAC Cooling Coils and Refrigeration Equipment, Cleaning and Disinfecting, Non-Abrasive
• SpeedyFoam Condenser Coil Cleaner (non-acidic, biodegradable, alkaline, foaming cleaner), Tel: 888-700-3540 https://www.speedclean.com/
  
  Website Excerpt:
  
  SpeedyFoam is safe for coated and uncoated coils. It is an acid-free, alkaline, non-caustic, degreasing foaming formula. (Say that ten times fast, I dare you). It’s safer for employees to use, more effective on grease and works great on all metals and has a clean, fresh scent.
  
  Plus it’s 4x concentrated, so you get more bang for your buck. It’s designed for use with CoilJet and Condenser Needle but can be used with pump sprayers too.
• Superior Industries offers FCC-300™ non-toxic foaming spray coil cleaner and "conditioner".
• Total Coil Cleaner (Acidic),
• CONTACT us to suggest additional coil cleaning products

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

$60 to sprinkle powder on my A/C cooling coils? Worth it?

I paid $60 for my HVAC guy to sprinkle some kind of powder over the coils of the air handler which he said the condensation running down would clean the pan and the pvc drainage pipe... what was that? - On 2019-08-12 by Pj -

Reply by (mod) - HVAC guy to sprinkle some kind of powder over the coils

Without a product name we can only guess that it was perhaps a water-activated foaming cleaning and disinfecting agent. It's not the greatest treatment but it might help.

Can't find cleaning access for the coils

I've seen and read several pages on how to clean the AC evaporator attached to a central air furnace.

All the info shows removing a panel/side off the box around the evaporator, then commonly removing a shield/wall of the side of the evaporator itself to access the fins etc.

However on mine, there are no removable walls/panels on the box to get at the evaporator, it looks custom built out of ducting box stuff and not made to come apart at all.

There is only a single small access hatch (8x8") to access some plumbing and you can also see the serial # and model of the evaporator. What's the deal, did they really build it (before I bought the house) and not leave access to the AC?

Only real options I can think is somehow cutting a much larger access panel, but there are pipes and hoses running around in there and I could easily cut something. Any advice? - On 2019-07-31 by Dale

Reply by (mod) -

Unless you missed something, it sounds as if you're right, the installer didn't provide a cleaning access. Typically the cleaning tech has to cut an opening and fabricate a sealable panel for future cleaning.

Bacteria was spewing out of our A/C coil

I had a very haywire A/C problem which had bacteria spewing from each vent in ceilings causing severe sickness but-that's a whole other question. After a supposed "inspection" I took the filter off and found this stuff from where standing water had pooled.. apparently not cleaned, can this produce even more harmful toxins to circulate?

Is this bad especially if "professionally" checked?

Thank You! - 2019-03-05 by Hannah

IMAGE LOST by older version of Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

Reply by (mod) -

HannahI can't tell what we're looking at - in the photo that is.

The red areas look blurry but perhaps like rust.

Watch out: But there can be harmful bacterial as well as mold growth in HVAC condensate,

I suggest following the cleaning and maintenance advice found

at Legionella BACTERIA & HVAC EQUIPMENT 

and at WISCONSIN PROTOCOL for CLEANING HVAC

On 2017-06-04 by l imran

please help me i have split ac install at my home indoor & out unit. yesterday i cleaned my indoor unit because of dirty after cleaning i install if agane now the ac cooling is very low air is not very cool like before clean outdoor unit gas pressure is ok compressor ok condenser is ok every think ok but cooling not good room temp, maximum 27-26 instant of 20 . could any one help me please

Reply by (mod) -

Imran

If you use the search box just above to find our article on

HVAC AIR FLOW IMPROVEMENT

, you will see a checklist of things that you should examine in diagnosing the problem that you have described.

Should I spray our A/C with vinegar every week as a deodorizer?

I am very chemically sensitive. I am going to have a yearly ac check soon. My ac is almost one year old. Can a spray bottle of vinegar/week (how much) be used to clean the coils. The company I use , uses deodorizer which I cannot have done. thank you. On 2017-04-29 by audrey

Reply by (mod) - The "deodorizer" isn't the important step and in fact can be a "bandaid" approach.

The "deodorizer" isn't the important step and in fact can be a "bandaid" approach.

What's important is that the cooling coil be actually cleaned - IF NEEDED - that is, if it's blocked by dust, dirt, debris. Typically companies who do this cleaning with the coil in place by vacuuming and using a foaming cleaner that's caught on a tray below. A deodorant spray isn't a substitute for cleaning. Vinegar is a mild household cleaner that has widespread use and has been used in HVAC systems.

I agree with Fugler (2004) that HVAC equipment must be actually cleaned before people can apply biocides, sanitizers, etc. The cleaning is the more-important step.

• McNeice, Russell. "Method of Increasing Efficiency and Reducing Thermal Loads in HVAC Systems." U.S. Patent Application 14/149,631, filed January 7, 2014.
• Fugler, Donald W. "Duct Cleaning: Do Homes Need It?." ASHRAE journal 46, no. 6 (2004): 28.

Yearly Air Conditioning Maintenance Matters

Ekh said:
Yearly Air Conditioning Maintenance Matters

There has been some question from my customers in the past few months about heating and air conditioning Cleanings and their importance to the proper operation of the equipment. I wanted to write this article to discuss a few important issues that can occur in absence of the annual maintenance.

There are two important cleanings that need to be performed by a qualified heating and air conditioning company to ensure safety and proper system operation. For the sake of this article we will split up the cleanings into two separate articles (furnace cleaning and air conditioning cleaning) and only discuss one at a time.

Air Conditioning Clean and Check every year

After an entire winter of being dormant and not in use, an air conditioning system has a big job at task upon first starting up for the summer. The way an air conditioning condensing unit (outside unit) works is by changing the state of the refrigerant in the system from a liquid to a gas.

This generates a heat transfer and cools the air through a coil inside your home. So after 7 months of not being used the component that compresses the refrigerant back to a liquid has not been used and lubricated through the refrigerant

Question: is acid cleaning the cooling coils necessary?

(Oct 28, 2014) Dennis R. Sullivan said:
Is acid cleaning of coils necessary?

Reply: no

No, Dennis, it's not necessary and may be risky to use corrosive acids to clean HVAC evaporator coils. There are specific coil cleaning sprays and products formulated for that purpose. But yes, if a cooling coil or evaporator coil is clogged it must be cleaned for the HVAC system to operate.

Question: relationship of blocked cooling coils and the HVAC compressor

Can it be said with 100% accuracy that a blocked evaporator coil can cause the compressor to ground? Also, is the evaporator coil usually cleaned with a maintenance plan? Thank you. - Feb 10, 2015 R Koch

Reply:

R Koch:

"Cause a compressor to ground" - huh? If you mean is the evap coil necessarily electrically grounded, no. You sound too much like a lawyer hoping to sue someone. But I'll answer you anyway.

About annual HVAC maintenance plans, they vary all over the place in my experience. Typically the plan will

- include an annual inspection

- an annual check for proper operation

- repair or replacement of defective parts included in the "inclusion" list
and vague language such as
"annual maintenance plan covers the diagnosis and repair, replacement or adjustment of the specified parts within your Cooling Unit as deemed necessary by our Authorized Service Technician"

Nothing in the sample plans I reviewed specifically indicated evaporator-cooling coil cleaning.

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: 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: 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: how often should you acid-wash the air conditioner coils?

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: 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 from 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?

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 - (Aug 5, 2012) david n. simmons said:

Reply: water beneath the coils - tech says condensate drain line

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.

 

Question: cause of a dripping sound from the evaporator

I noticed last night a louder than normal dripping sound coming from my evaporator. After inspecting, I see there is rust around the copper tubing and along the bottom where the evaporator sits on top of my furnace. The condensation is evacuating from the drip tray properly, but the rust has me concerned. Is there a way to prevent any further corrosion? - (Aug 17, 2012) R.Black

Reply:

sounds as if a condensate drain is clogged - leading to pan overflow. Watch out also for dangerous damage to the furnace heat exchanger.

Fix the clog and / or leaky condensate pan.

Ask your heating service tech to inspect or test the heat exchanger for leaks and safety - avoid a carbon monoxide fatality.

Question: tried compressed air to clean the cooling coil - no good. what other coil cleaning options are there for an inaccessible coil?

I tried using compressed air but i am not getting very far. Spray is hard to get in from the inlet, almost working blind if i do that. The foam sounds like a good solution for me. Is it ok to apply on the clean side (outlet) of A-coil? What are my options? Nick Chicago

Reply:

Cleaning

Squirting coil cleaning foam onto the clean side of the cooling coil will probably not be effective. A pro would make an access opening if necessary, then close and seal it when cleaning is complete.

Question: Can alcohol corrode heat pump coils?

Can alcohol be a corrosive agent in cleaning heat pump coils? It has been serviced 3 times for "Dirty Sock Syndrome" but the cleaning agent and antibacterial deodorizer recommended by service agent did not work. If not alcohol, what other materials would you suggest? - (Feb 20, 2013) Keith

Reply:

Keith,
Alcohol would not be likely to harm metal components but might be a problem for sealants or some plastics or other gaskets.

 

Question: how to remove corrosion on outside AC coils - caused by dog pee

How to remove corrosion on outside ac coils from dog pee? I can see the corrosion on the inside of the unit.I was going to try that foam cleaner form the Home Dept. IS my unit ruined? the corrosion is only on two corners and about 5 inches high. (Apr 2, 2013) Sherri

Reply:

Sherri,

Using a commercial coil cleaner will remove some corrosion and debris and odors. I would not try using anything too aggressive on corroded HVAC coils out of worry that we dissolve the fins entirely. If the coil is badly corroded it means that airflow through it and heat transfer are retarded, decreasing system efficiency and increasing operating cost.

One might consider replacing the coil but the cost is high enough that as long as the AC or Heat pump is working in my OPINION you won't earn back that cost very quickly.

On the other hand if the equipment is old and on last legs, this is time to start thinking about replacing the unit.

Question: odd heat pump odor when changing from heating to cooling mode

I have one year old heat pump unit and the only problem is when I go from Heat to a/c the indoor unit gives off a very odd oder. Not when I go from a/c to Heat. 4/2/14 Bruce l

Reply:

Bruce let's think about what's different switching from heat to A/C vs A/C to heat. Typically the same blower fan, ductwork, and air registers are involved in both modes.

What's different is the direction in which refrigerant is circulating inside the system - not something that would explain an odor difference. Also different is that in cooling mode you're probably producing condensate, perhaps operating a condensate pump. I'd look at that system to start.

Question: crud on the cooling coil, limited work space, will the tech do a better job than I can

I have taken off the cover for the evaporator coil and determined that the supply side is clean but the inside of the coil has a good sheet of crud covering it. I have a very small space to work and am unable to put something inside the unit to prevent the crud from falling down into the blower.

With this concern I have contacted an HVAC Co. and have an appt for them to come and clean the unit in place (not taking it out).

My question to you is what if anything will the technician do to prevent the crud from falling into the blower.

I suppose they could remove the furnace assembly below and then have some access for placing a piece of plastic. Before I spend $260 i want to know that the technician is going to do something more than I could do myself. - 4/5/14 Darren said:

Reply:

arren,

Typically they use a foaming cleaner that drips through the coil into a pan. It may be that the blower assembly needs to be removed for proper cleaning.

You're dead right to ask for specifics about what they're going to do. But usually someone with experience at methods for cleaning hard-to-access cooling coils knows some tricks of the trade that you may not. Or she/he may simply make and then re-seal an access opening.

Question: do it yourself fan coil unit coil cleaning

I am new to the game of cleaning my own FCU coil. So far i am still doing very basic stuff; i have this really low power hand operated spray which sprays on an organic detergent which was designed for cleaning the coils. I usually let the detergent do its work for 10 minutes before i use a hand pump sprayer to flush the coil with water. i read that there is a big problem of dislodging mould spores when performing such cleaning.

I am inclined to believe that i need a high pressure water jet to dislodge the said mould spores from the coils. So i am thinking of revising my strategy.

I will continue to spray the coil with the same organic detergent but i will use a high pressure water jet to do the flushing. Is this new strategy sound?

I am looking between a hand crank portable pressure jet cleaner that puts out pressure at 36psi tops and a electrical pump cart that can achieve 1000psi. Is the latter overkill? Need some sound advice. Thanks! - (May 4, 2014) Eric

Reply:

Eric,

The mold that *might* be on the coil ought to wash off with the washwater into whatever container you are using.

Using high pressure water, if you're not experienced, could bend and damage the coil fins and blow crud all over the place.

Eric said:
Thanks for replying . I have seen a local aircon cleaning vendor do it in his youtube videos. Meanwhile i have purchased a pressure jet cleaner that puts out pressure 145 psi tops. the danger of coil fins bending notwithstanding, do you have any advice or tips on how to go about jetting the coils gently? Thanks

Reply:

OPINION: Approach from a distance, keep spray at right angles to fins, prepare to capture and handle the mess you'll stir up, take care with aim not to blow water, air, or debris where it's going to do damage: into the ductwork, onto electrical components. Protect your eyes.

 

Question: use bleaching powder to clean the AC evaporator in a car?

Can i use bleaching powder for cleaning an ac evaporator of a car

reply me in jazzomar@gmail.com - (May 28, 2014) Omar

Reply:

Omar,

I'd be careful about damaging the coil with anything that may be corrosive, OR that would be hard to clean off or remove. For a car cooling coil, which indeed could need cleaning if the filter were missing or failed, I'd see what the car service manual recommends.

Also if you over-do the bleach you may have trouble getting rid of the bleach smell.

 

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Continue reading at FROST BUILD-UP on AIR CONDITIONER COILS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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