How to clean evaporator and condenser coils


08 September 2015
Dirty condenser coils before - acr journal
In the second “How To…” article by AC&R service and maintenance experts Advanced Engineering, we discuss the problems caused by dirty evaporator and condenser coils, and describe several methods for effective coil cleaning.

A basic air conditioning system consists of indoor cooling coils or evaporators and outdoor condensing coils (these can be either air or water-cooled).

Every part of the operating system must function correctly to accomplish the cooling job efficiently.

The coils are the parts of the system where the heat transfer takes place and dirt on a coil will form a barrier to heat transfer – effectively insulating the coil. Heavy dirt build up can also clog the coil and reduce air flow.
Dirty, clogged coils can cause many varied problems:
  • Reduced heat transfer
  • Decreased cooling capacity
  • Increased energy consumption
  • Increased operating pressures and temperatures
  • Increased wear on the system, which can lead to component damage, system malfunctions and reduced life expectancy
  • Reduced energy efficiency
  • Poor indoor air quality and potential for contamination (evaporators only)

Before you begin cleaning, it’s important to note that a high-impact pressure washer should not be used to clean air conditioning coils. The water pressures involved can easily damage the coil’s delicate fins; and it is also very easy to push dirt further back into the unit and out of sight, making it much harder to remove.

Low pressure systems like our own HydroSprayer coil cleaner applicator are specifically designed for the job and avoid any of the physical damage associated with household pressure washers.

Cleaning the coils


SuperClean is a heavy duty condenser cleaner with a powerful foaming action. Because it’s heavy duty, it is especially suitable if a unit is particularly dirty or has not been serviced or used for an extended period of time.

Before you start any cleaning job, you need to ensure you are wearing the recommended personal protective equipment, which in this case includes safety glasses and a pair of protective gloves.

Since SuperClean is a concentrated product, it first needs to be mixed with water. Combine it to the ratio one part SuperClean to three parts water.

The easiest way to mix is to measure and add the fluids directly into the HydroSprayer. Usually warm (but not hot) water provides a faster cleaning reaction.

Since SuperClean is a foaming cleaner, it is recommended to start at the bottom of the coils and work across and up with the HydroSprayer. If you start at the top, the foam would naturally run down the coil making it very difficult to tell what has or has not been cleaned.

Once SuperClean has been applied in this way you should wait ten minutes for the foaming action to do its work. You’ll start to see the chemical reaction taking place: the foam will develop as it pushes the dirt and debris from the centre of the coil outwards.

Then the coils should be thoroughly rinsed with fresh water. This time, though, it is recommended to rinse from the top to the bottom so you’re not washing dirt onto cleaned areas below.

It’s important to rinse thoroughly with water so no residual product is left to react when you’re away from the unit.

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Gentler alternatives


If an engineer prefers not to use a powerful, heavy duty cleaner, EnviroCoil can be a preferred alternative.

EnviroCoil is a universal coil cleaner that is biodegradable, environmentally friendly and suitable for use inside or outdoors. It is gentler than SuperClean and ideal for systems that are regularly maintained.

Hassle-free direct spray coil cleaners

EasyFoam - acr journalEasyFoam in action

EasyFoam is another powerful foaming condenser cleaner, but it comes in a convenient, easy-to-use, ready-mixed aerosol. It is perfect for removing stubborn dirt and for use on deep, multi-row condensers.

The main benefit of EasyFoam is that it is much faster and more efficient to apply than concentrated cleaners because it doesn’t need to be pre-mixed on site.

You also don’t need to use a low pressure HydroSprayer – instead you spray EasyFoam directly onto the coils. As with SuperClean it should be rinsed off after use.

RTU CC (Condenser Cleaner) is a handy, ready-to-use biodegradable condenser cleaner in liquid spray form. It comes pre-mixed with its own sprayer, so it’s ready to go straight away.

RTU CC is generally recommended for regular routine (preventative) maintenance. If your coils are particularly dirty or have been left unattended for some time they are likely to require a more heavy duty cleaner.

Since it is is not a foaming cleaner, RTU CC should be applied across and down, from top to bottom. Apply the cleaner by spraying it directly onto the coils.

Once you have sprayed the exposed coils you should again wait ten minutes for the cleaner to be at its most effective. Once the ten minutes is up, the service engineer should thoroughly rinse the unit with fresh water from top to bottom.

As with SuperClean, a low pressure HydroSprayer is generally recommended for rinsing, but if an engineer doesn’t have a similar system s/he can always rinse out the RTU CC sprayer bottle with water and use it to spray water onto the coils to rinse the unit thoroughly. As you rinse you will see flecks of dirt rinsing straight off the coils.

EasyFoam After Cleaning - acr journalEasyFoam After Cleaning

If you would like specific advice on how to clean your evaporator or condenser coils, contact the experts at Advanced Engineering on their support hotline: +44 (0) 1256 460 300 or visit their YouTube channel for more cleaning tips and guidance.