Air Conditioner Filter Cleaning

air conditioner filter cleaning
Air conditioner filter and air handler

Air conditioner Filter cleaning rids dust off your AC sieve.

The air filter’s work is to clean the indoor air that you breathe. It does that by straining particulates found in the conditioned room’s air.

An air conditioner installed with a technical precision should serve you for years before any major breakdown. You only need to do minor routine maintenance that your AC manufacturer recommends. One of these regular maintenances is air conditioner filter cleaning, or changing the air filter in the case of a disposable filter.

If you don’t clean or change the air filter at the right time, your AC’s cooling efficiency will downgrade.

Suppose your AC has been performing well. Suddenly, you notice a glitch like “no cooling from your indoor unit. Or, the cooling becomes inefficient.” Such anomaly could be an underlying filter related-fault. Using your AC for long without giving it necessary maintenance can cause such a fault.

If you’re the AC owner and you have HVAC expertise, it’s easy to diagnose and work on your AC. But if you don’t have the skill, little ambition is enough for you to handle some DIY fixes.

However, if you are less interested in the hands-on aspect of service and maintenance, read on to learn a thing or two about your air conditioner filter cleaning. It’s resourceful to have a rough idea of the work an AC technician would do on your machine.

So let’s look into the faults that can require air conditioner filter cleaning, to solve.

Lack of air conditioner filter cleaning can result in inefficient or no cooling.

The cooling effect of an AC happens at the air conditioner evaporator tube. The evaporator tube is also called indoor heat exchanger. It is bundled in one unit called Indoor Unit (shown below).
AC indoor unit
An indoor unit that holds the air filter
The indoor unit of a ductless split AC is installed in the conditioned room. But a Central Air Conditioner’s evaporator is in the Air Handling Unit that sits outside the conditioned room. Many Central AC designs place the AHU in the basement or attic. In houses without a basement or spacious attic, it sits in a convenient spot outside the conditioned rooms.
In a ducted system, the evaporator fan draws air from the conditioned room via the return side of the duct. AC air filter cleans the air before it reaches the evaporator coil surface. The evaporator fan pushes clean low-temperature air through the duct. Nothing but clean air should flow across the evaporator fins.
After your AC has run for one to three months, dirt and dust accumulate on the filter. This dust clogs the filter. The clogging can happen sooner or later than three months, though. It depends on how clean your environment is. Smoggy and dusty environment means the filter gets dirty sooner.
Then the time for filter cleaning or changing comes. To understand how important this maintenance measure is, compare it with changing your car’s air filter. What do you think would transpire if you don’t change your car’s air filter according to your vehicle manufacturer’s recommendation? Your engine will choke.
Likewise, if you don’t clean or change the AC filter, air circulation will be impaired. And although you’ll be running your AC for longer hours, you’ll still experience reduced cooling. A clogged filter can also lead to icing of evaporator tubing.
So if you experience reduced cooling, first check the AC air filter.

Air Filter

The air filter is an element of AC that eliminates foreign particles from the air you breath. It has tiny pores that allow air molecules through but blocks dust and dirt from reaching the evaporator tube surface.

In a ductless split-phase air conditioner, the air filter is in the indoor unit. But in a duct system AC, it’s within the Air Handling Unit assembly.

The two types of filters are reusable and disposable filters. When you service your AC, you clean and use again reusable filters, but throw away disposable filters.

The degree of filtration defines the quality of a filter, and the quality of a filter defines its price. A medical filter used by individuals with allergies costs higher than a normal filter.

Dust and dirt sieved by the filter form a layer on the filter after weeks of operation. This dust blocks filter pores and hinder free air flow. The resultant effect of this phenomenon is impaired airflow across the filter and evaporator coil. Eventually, there’ll be no sufficient cool air coming from the indoor unit; not until you clean the filter.

Let me explain the simple air conditioner filter cleaning procedure using the photo below:

AC Air filter
Indoor unit with washable air filter

Before cleaning the filter, switch off the AC at the wall switch or use interface remote control.

  1. Pry the front evaporator cover open. A split indoor unit has a pair of reusable filters. In my example photo above, it’s a washable fine plastic gauze.

  2. Pull the filters out. If the AC has operated for one to three months without cleaning the filter, it’s now full of dust and dirt.

  3. Use a hand blower (if available) to blow off the dust from the filter, then scrub it with a soft brush in soapy water. Put it out in the sun to dry before you insert it back into the indoor unit.

  4. As the filter dries out, you’d want to find out if the indoor unit has gathered dust hidden in inaccessible joints – in most cases, there is concealed dust and dirt.
    Use a portable vacuum cleaner (with nozzle) to suck up the hidden dust.

Ductless split AC filter
Air filter of a ductless AC
Duct AC air filter
Air filter of an AC with a duct system


The two procedures for cleaning or replacing ductless or ducted AC systems don’t differ much. A duct system has its filter secured in place with screws at the AHU. Locate the screws, unscrew, and remove the filter. Clean and put back, or replace if it’s a disposable filter.

If you ignore air conditioner filter cleaning, it compounds filter-related problems. Your AC electricity consumption will rise. That’s not good news because your cooling system already accounts for nearly 50% of your home power consumption when it’s functioning normally.



Air Conditioner Machine. What Is It?

Air Conditioner machine Indoor Heat Exchanger
Split-type air conditioner machine’s indoor unit

An Air Conditioner machine is the equipment for lowering room temperature at home, in the office, or in a car. It works on the same principle as the refrigeration cycle.

An air conditioner machine’s other short names are AC, A/C or ac.

The Air Conditioner inventor’s original idea was to lower the temperature of a given indoor area. But over time, design-works incorporated a mechanism that does the reverse of cooling. So when you press a button, an AC can also heat the room.

A technology called heat pump is an example of a reverse refrigeration cycle. You activate a special valve from your AC control panel, and the AC absorbs heat from the outside environment and transfers it into the room.

Another form of heating in air conditioning is an electric heater. It’s an element inside the AC that generates heat and then a fan blows the heat into the conditioned room.

In cold weather, when the heat pump or heater is not able to provide enough heating, a furnace is the alternative.

A furnace is a dedicated machine for generating heat by burning fuel or boiling water. It’s either a stand-alone installation or it is part of the main AC unit. If it is an embedded furnace in the AC infrastructure, the AC’s air handler fan pushes the heat it generates into the room via the same AC duct line.

Since Willis H. Carrier invented the AC in 1902, expert designers have expanded on his work. They’ve redesigned air conditioners to suit different House Air Conditioning and Vehicle Air Conditioning applications.

Air Conditioning Industry classifies house air conditioners into Central air conditioners, Packaged air conditioners, Split type air conditioners, and Window type air conditioners. Particular application informs what designers come up with. That means a mini-split AC would be a practical installation for a 150 square feet room instead of a central air conditioner with a duct line.

Automobile air conditioning application work in small cars, commercial trucks, and refrigerated containers.

The refrigeration industry measures an air conditioner’s size, or capacity to cool in Ton, or British Thermal Unit (BTU).

In the early years of refrigeration before the invention of household refrigerators, vendors had centrally located ice stores in towns. Here, residents bought ice to use at home. The vendors measured cooling capacity by how much cooling a ton of ice did.

Refrigeration industry later borrowed the term “ton.” And the British standardized “one ton” to 12,000 British Thermal Unit (BTU).

You can see your AC’s capacity displayed in ton or BTU on the condensing unit or evaporator unit.

With the current global climate change, temperatures overwhelm. Heat in hot seasons is getting intense, and winters cause discomfort. The extreme temperatures are fast making an air conditioner a necessity. If you don’t own a home or office AC yet, chances are you would soon.

That’s why you need to have basic information about air conditioners; what you should know before you buy your home or office AC. This can enable you to make an informed decision before you buy.

But if you already have an air conditioner at home or in the office, you can learn the basic maintenance tips. Some simple do it yourself (DIY) can help you evade avoidable service disruption. You can also save on tangible bucks payable to a call technician and empower yourself to defeat repair scams.

An air conditioner machine is like any other mechanical equipment that needs simple regular maintenance to prolong its life and avoid a major breakdown. You need to know which parts need regular dusting, tightening of loose nuts, and general cleaning. Such maintenance is also good for car air conditioners so as to avoid inefficiency and respiratory side effects.

Refrigeration Cycle In Air Conditioner

A basic understanding of what happens in compression refrigeration

refrigeration cycle of air conditioner
Refrigeration cycle diagram of Air Conditioner

Refrigeration cycle is the movement of refrigerant that transfers heat from one heat exchanger to another in a refrigeration system. The two heat exchangers are the condenser and evaporator. See the photo above.

Refrigerant is the chemical substance that refrigeration systems use. Ammonia, propane and carbon dioxide are examples of refrigerants in refrigeration systems.

Refrigeration is the technology behind the workings of air conditioners, heat pumps, and refrigerators.

There are two main types of refrigeration cycles – compression refrigeration and absorption refrigeration cycles. But I talk about compression refrigeration cycle in this article.

While a compression refrigeration cycle system has a compressor that compresses and pumps refrigerant in the system, absorption refrigeration cycle uses an external heat source to heat refrigerant to boiling point.

I have used a split phase air conditioner system to expound on this subject.

Even though all air conditioner systems have components that function in a similar way, yours could be slightly different in shape and design.

Let’s refer to the refrigeration cycle in the diagram above:

The refrigerant moves from point 1 to 3, 4, 5, 6, and then back to point 1. Component 1 is the compressor, 3 condenser coil, 4 refrigerant filter, 5 expansion device, and 6 evaporator coil.

Metal tubing joins together the five components in a closed circuit that forms a refrigerant flow path. Copper is the most used metal because it has a better resistance to oxidation.

As the refrigerant moves inside the tubes, it changes state from high pressure-high temperature to low pressure-low temperature. The change of state between point 3 and 6 is what causes air conditioning effect.

Components 1, 2, 3, 4, and 5 enclosed in the black line rectangle make up the condenser unit. Components 6 and 7 in the blue rectangle form the evaporator unit. These condenser and evaporator units have their electric control circuitries attached inside their individual casings as shown below:

Refrigerant cycle indoor and outdoor unit circuitry
Condenser and Evaporator Unit circuitry

Components in a refrigeration cycle:

Compressor pump

AC Refrigeration cycle compressor
Refrigeration cycle compressor

Compressor motor is the heart of a compression refrigeration cycle. As the name denotes, it compresses and pumps refrigerant in the air conditioner tube system. The compressor has three refrigerant lines:

  • Discharge line carries compressed high-pressure refrigerant to the condenser coil.
  • Return line carries low-pressure refrigerant that flows back into the compressor.
  • Charging line is used to charge refrigerant into the system.

To explain what happens during a refrigeration cycle, let us look at two of the thermodynamic laws that make refrigeration possible.

Law one: “… in a closed system, you can neither create nor destroy energy, but can change it from one form to another.”

Law two: “… heat moves from a high-temperature material to a low-temperature material.” But with some work, heat can move in the reverse direction.

So, the compression refrigeration cycle begins and ends at the compressor. The compressor’s suction line draws vaporous refrigerant from evaporator coil through the return line, compresses it, and pumps it into the condenser coil.

Condenser Fan

AC condenser fan in refrigeration cycle
AC condenser fan

Component 2 is the condenser fan that blows ambient air across the condenser tube. Ambient air is still, and its temperature is lower than that of the refrigerant in the condenser coil. The fan facilitates the air movement to enhance cooling.

Condenser Coil

Refrigeration cycle condenser tube
Condenser tube

Component 3 is the condenser coil, also known as outdoor heat exchanger.

The compressor pumps high-pressure high-temperature refrigerant into this condenser. As the refrigerant flows from point a to b, its heat is rejected to the outside environment. Remember, heat moves from a high-temperature material (in this case the refrigerant) to a low temperature one (in this case air surrounding condenser).

Inside the condenser, vaporous refrigerant condenses into liquid form. Condensation is a vital aspect of the refrigeration cycle because, in the stage that follows, which is the evaporation stage, liquid refrigerant uses every bit of heat energy around the evaporator to boil and evaporate. Hence, a space void of heat energy is created.

Streamlined condenser fins direct airflow across the condenser coil. Read about cleaning your condenser to know why keeping your condenser dust-free ensures optimum heat exchange.

 Refrigerant Filter

Refrigeration cycle filter drier
Refrigerant filter drier

Component 4 is the refrigerant filter drier. It is a copper or steel container with desiccant.
It is connected in series with the refrigerant tube. Its position is just before the refrigerant enters the expansion device. Its duty is to absorb – actually adsorb – water and moisture that could accidentally find its way into the refrigerant line. Moisture or water has the potential to condense and freeze, blocking the metering device. Such a blockage can damage the compressor.

The filter also blocks semi-solid impurities that come from internal wear and tear. Such could block the metering device if it is a capillary tube.

There are different types and sizes of filters for domestic and commercial applications.

Metering device

TEV and capillary tube for a refrigeration cycle
TEV and capillary tube

Component 5 is the metering or expansion device. It restricts refrigerant flow to reduce the pressure of refrigerant entering evaporator coil.

Two examples of expansion devices are capillary tube and Thermostatic Expansion Valve (TEV). A capillary tube is a fixed-opening type expansion device and TEV is a variable-opening type. The size and type of your installation will determine which metering device you use. But they both do the same work of refrigerant restriction.

Evaporator Coil

Refrigeration cycle indoor unit tube
Refrigeration cycle indoor heat exchanger

Component 6 is the evaporator coil. Also known as the indoor heat exchanger or indoor unit, it is where the air conditioner’s actual cooling effect takes place.

What happens here is that as low-pressure refrigerant enters the evaporator from the expansion device, it begins to boil. For boiling to occur, the refrigerant absorbs and uses heat energy from the space around the evaporator coil. Heat deficiency occurs where refrigerant has drawn heat. The result is cold temperature around the coil.

Evaporator fan

Refrigeration cycle indoor heat exchange fan
Evaporator fan

Component 7 is the evaporator fan. The refrigerant in evaporator tube absorbs heat energy around the tube. Then the fan facilitates circulation of the remaining low-temperature air around the evaporator coil into the conditioned space.

This split-unit evaporator fan is different from the condenser fan in design. It is cylindrical and aligns with the evaporator coil, stretching from one end of the evaporator coil to the other.

Refrigeration cycle summary

  1. The compressor suction line draws vaporized refrigerant from the low-pressure side of the evaporator. It compresses and pumps the high-pressure high-temperature refrigerant into the condenser coil.
    With the pump having done some work of compression to the refrigerant, the now hot refrigerant loses the heat it absorbed from the evaporator to the outdoor environment.
  2. Expansion device restricts liquid refrigerant flow into the evaporator, reducing its pressure. Immediately low-pressure refrigerant enters the evaporator, it begins to boil.
  3. The refrigerant in the evaporator absorbs and uses heat energy around the evaporator coil to boil, leaving the space surrounding the coil without heat. Thus space, where heat is removed, is left cool.
  4. At the end of the evaporator coil, the vaporized refrigerant is sucked back into the compressor and the refrigerant cycle starts again. The conditioned room becomes cooler and cooler in the process.

If an installer sets up an air conditioner with precision, it will go on for years before any major breakdown occurs. What is important, though, is regular maintenance. Just as your car needs regular service, your air conditioner does too.

A functional thermostat and other controls keep your air conditioner working within its capability range.