A/C coils and their cleaning

There are two coils in your air conditioning unit:

  • The evaporator coil is located in the indoor section of the ac unit
  • The condenser coil is located in the outdoor unit.

Both coils are an integral part of your air conditioner and need to be kept clean for optimum performance and also reduce the chance of failure of other components of the ac system .

Evaporator coils

The evaporator coil is located in the indoor unit and has the following function:

  • The air from the conditioned space passes over the air filter and then to the coil.
  • The fan moves the air over the coil.
  • As the refrigerant in the coil is cold, heat is removed from the air into the refrigerant.
  • This cold air is then blown back into the conditioned space to give the comfort conditions required.

Condenser coils

The condenser coil is located in the indoor unit and has the following function:

  • The condenser coils remove heat from the refrigerant.
  • The hot air from this heat removal is discharged from the condenser coil by the fan to the ambient air.
  • This allows the cooled refrigerant to travel back to the evaporator coils.

What can affect coil performance

There are various factors which can affect the evaporator coil and condenser coils performance:

  • Dirty or blocked ac filters
  • Fans not operating
  • Bent fins on the coils
  • Debris (leaves etc) on the condenser coils.
  • Hail damage to the condenser coils.
  • Dirty coils

Why is it important to clean your ac coils?

It is important on all air conditioners to ensure the ac's coils are clean:

  • Most air conditioning coils are copper coils with aluminium coil fins.
  • Poor air movement over the coils reduces the heat transfer effect required.
  • As the air passes over the coils it allows the cooling function to operate correctly.
  • Clean ac coils will ensure your hvac system is working properly.

How often should you clean air conditioner coils?

Various factors determine how often the coils in your ac system should be cleaned:

  • In residential applications, this should not be required very often.
  • In some commercial situations eg Hairdressers, Pet Grooming Salons, the ac evaporator coils will require more regular cleaning as the indoor air will carry more dust etc. The air filters will also need more regular cleaning.
  • As with evaporator coils, clean condenser coils are also a must for the cooling process to operate efficiently.
  • Leaves and other debris can lodge on the condenser coil and reduce the air flow leading to lack of performance of the ac unit.

Can I clean air conditioner coils myself?

The short answer is no.

A Professional hvac contractor should be engaged to carry out regular maintenance and coil cleans when necessary.

Attempting to clean these yourself can lead to damage of other components of the air conditioning system.

How are air conditioner coils cleaned ?

Evaporator coils:

Initially, the electrical circuit breaker must be turned off.

The access panel adjacent to the coil is removed to gain access to the coil.

In some situations, compressed air may be used to blow out any dust in the coil. Care must be taken to ensure aluminium fins are not bent over from the air pressure.

The preferred method is using a commercial cleaner and pressure washer:

  • it is important to make sure the drain pan and drain are clear to allow the water to run away from the unit
  • the coil is sprayed with ac coil cleaner using a spray bottle or garden sprayer and then left for a short time to lift the dirt and debris from the coil.
  • a pressurised water spray is then used to wash all the dirt and grime from the coil.
  • in large central system plants, a steam cleaner is sometimes used.

Once the coil/s have been cleaned the access panels can be replaced.

The circuit breaker turned on and the system re-started

Condenser coils:

Condenser coils can be damaged by hail and other items hitting them.

  • This will lead to bent fins. These can be straightened by careful use of a fin comb.

Leaves and dirt are also common in condenser coils as they are quite often installed at ground level.

  • These can be cleared at times by the use of a garden hose.
  • The water can also be hosed through the opposite direction to loosen any debris in the coil.
  • Coil cleaner can also be used on these aluminium coils.


In the middle of summer and your ac unit is delivering warm air, it is time to check on some items.

  • Check that your air filter is clean.
  • The coils may be dirty and require cleaning.

Always get a professional hvac contractor to carry out these service works as this will save money in the long term.

Coil cleaning in both indoor units and outdoor units will lead to better performance of your ac systems.

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