Common Aircon Problems, Their Causes, And Repair Options

The recent studies on climate and temperature have found that 18 of the 19 warmest years of the world have occurred since 2001, this is precisely what will happen if you don’t take care of your air-conditioning unit.

According to the Meteorological Services Singapore, December 2018 was the second warmest December in Singapore with a temperature of 27.6degree Celsius.

One of the ways to deal with this rising environmental heat is a well-maintained aircon system. This device takes the hot air from the surrounding and regulates its temperature to a level that is suitable for you. It also manages the humidity, pollution and proper airflow of your home and offices.

Like any other electric equipment, an aircon can also have several problems and issues during its lifetime. These problems may be big or small; some of them may be repairable while others will need some aircon part’s replacement.

In such a situation, you must contact experts for a thorough inspection and aircon servicing.  We can help you to eliminate all of the following problems.

However, if you recognize the problems earlier or can determine their cause, there is a good chance that the problem will not escalate to a bigger one.

In this article, we will discuss some of the most common aircon problems that you might encounter during its use as well as discuss why these problems are caused in the first place. Then, we will also discuss their repair options so you can continue to enjoy the comfort of an aircon in the hot summers.

Why Is There An Awful Odor In My Aircon?

The smelling air flow of your aircon is a clear indication that the unit needs cleaning. With time, the mildew molds and many other bacteria settle down in the vents and start to reproduce which causes this problem. Clogging drain pan, liquid leaks and condensation of refrigeration coil may also contribute to the cause. 

The worst part of this defect is that it has a very severe effect on human health, especially the ones with respiration diseases. These mould spores travel from the duct to their lungs making them very sick. You can learn more in our article about why your aircon smells bad.

Causes And Repair Options

The only way to avoid all these problems is a professional aircon chemical wash or aircon chemical overhaul, and we can provide it to you. Our team cleans the system, disinfects it and even deodorizes it. We also offer chemical washes for aircon systems with high accumulation.

Read more about the difference between aircon chemical wash and overhaul

Why Does My Aircon Leak Water?

One of the most common problems that users usually face with their aircon is that it leaks water or liquid from some of its parts.

The refrigerant in your aircon system is free from water, and there is no additional storage or water inlet. However, there is still a condensation cycle that can lead to water leakages.

There can be several causes for this problem and their subsequent repair options, some of which are discussed below:

Causes And Repair Options

An aircon leakage problem can be caused by anyone of the following issues:

Clogged Drain Line

One of the most common reasons for water dripping from an aircon is that the drain line is clogged. The function of the drain line is to remove all excess water from the overflow pan and drain it outside. When it becomes clogged, water from the overflow pan starts dripping from the aircon unit.

To repair this problem, you will have to properly inspect the inner and outer units to determine what is causing the clog in the drain line. Once the exact location of the clogging has been identified, you can unclog it through various ways to remove all dirt, debris, and blockages so that the water can flow freely.

If the drainage pipes get clogged, it will cause water to leak inside the unit as well as the walls. If you notice that the walls around the aircon are showing signs of seepage, it may be because of the blocked drainage pipes. Cleaning them out and flushing all the debris from the pipe can result in fixing the problem of leakage.

Damaged/Faulty Overflow Pan

Another common problem of leaking aircon is that the overflow pan might have become damaged or faulty. Because of the damage, it will not be able to drain the water properly outside, and that will result in water dripping from various parts of the aircon.

To solve this problem, you have to inspect the overflow pan, carefully, to look for any cracks or holes in it. If they are small, you can repair the pan yourself by using any deep-action glue. However, if the damage to the pan is more, you will have to replace it.

The system has a dedicated evaporation unit that cools down the warm air, but in doing so, it also condenses the moisture in the air. This accumulated water drops to a pan and then travels out of the system through a drainage pipe.

However, with usage, dirt, dust, sludge, and mould block, the drainage pipe and lead to water deposit inside the system. Other factors for this clogging includes rusty or damaged drain pan, broken condenser pump, and dirty air filter.

Broken Water Pump

A broken pump can also become the cause for water leaking from an aircon. When the pump becomes faulty, the overflow pan will not be able to drain the water, the water overflows and drips from the unit. If the pump is broken, it is not a simple problem that you can fix yourself. A professional will have to assess the pump and then try to repair or replace it.

Incorrect installation of the air conditioner can also cause water leakage problems. If the technician fails to level the aircon units properly, the drain line will not be able to draw the water outside. And that can result in the dripping of water. In such a case, a professional will better be able to assess the problem and correctly reinstall the unit so that the problem resolves.

Aircon Does Not Cool The Room Effectively

An aircon unit that consumes a considerable sum of power but still does not provide adequate temperature control is not normal.

We have come across a lot of cases where the customer complains about sudden rise and drops in temperature.

If you notice that your aircon is not cooling your room effectively, there could be several reasons for it, which are discussed below:

Causes And Repair Options

Clogged Air Filter

One of the most common reasons for an aircon not effectively cooling the room is that its air filter is clogged. The function of the air filter is to catch all kinds of dust, particles, and debris from outside and prevent them from flowing in the air.

These foreign particles can cause the filter to get clogged, which will negatively affect the coolness of the aircon. To solve this problem, you will have to clean the air filter by washing it thoroughly and drying it completely before putting it back inside. However, if you are unable to clean the filter by washing it, you may need to replace it.

Faulty Thermostat

If an aircon is not effectively cooling a room, its thermostat may have to be blamed. If it becomes defective, it will not be able to regulate the room’s temperature and be unable to signal the aircon to start the compressor at the right times. Usually, this problem can be solved by repairing the thermostat or replacing it.

Improper Room Size

One reason for an aircon to not cool a room is that it may not be of the proper size as compared to the room. If the room is too big and the aircon has a smaller BTU, it will lack the capacity to cool a big-sized room. The solution to this problem is to get an appropriate-sized aircon depending on the room’s area.

Clogged Condensor Coils

Another common cause of an aircon not cooling enough is that the condenser coils may have become clogged because of dirt and debris from the outside. This blockage prevents the air from properly flowing through the coils thus, its cooling efficiency is compromised. The solution to this problem is to get the aircon serviced properly so all kinds of blockages can be removed.

Damaged Aircon Compressor

One of the most dreaded reasons for an aircon not effectively cooling a room is that its compressor may have broken down. This breaking down could be caused by several reasons, including not servicing the aircon regularly and letting small problems escalate into bigger ones. A damaged compressor usually needs to be replaced and cannot be repaired as easily.

Helpful Read: The Basics of Aircon Compressors

Aircon is Not Cooling the Room At All

Are you in a situation where the air conditioning unit is fully functional, but its cooling is almost zero? If yes, it may be due to one of the following problems in your aircon system.

All the air conditioner needs a specific refrigerant pressure for working and temperature controlling. If it doesn’t get adequate coolant, the amount of heat it absorbs from the indoor will decrease.

Its efficiency will reduce, and you will end up with an aircon system that keeps running for hours without any effect on the indoor temperature.

Helpful read: Why Isn’t My Aircon Cold?

Causes and Repair Options

Faulty Thermostat

This small apparatus is a type of switch which regulates the temperature of the aircon. Any change in this switch will prevent the free flow of coolant which means, minimal or no cooling.

Now, in a programmable thermostat, the issue may arise due to dirt deposit on the measuring probe, temperature setting, coding error, calibration error or a drained battery.

Lack of Coolant

Every air conditioning or refrigeration system uses a coolant for exchanging heat in and out of the system. However with time and continuous use, the coolant content decrease, hence the cooling factor depletes. In some cases, a small proportion of moisture in the refrigerant tubes can also lead to this problem.

The only option for dealing with this problem is with the help of a professional aircon servicing company like LK Brothers. Our team refills the coolant reservoir and also checks for other faults in the track.

We have some of the latest electronic as well as halide leak detectors along with some other common apparatus like fluorescent dyes, for the job.  We also have powerful pumps and solutions for removing clogging in coolant tubes.

Blocked Filters

When the air flows through the aircon system, it carries some dust particles and bacteria with it. There are various filters at different stages of the system which prevent these particles from reaching your house.

Over time, the deposit of these impurities blocks the screen and stops airflow, resulting in no cooling effect. It is also a potential cause of overstrained and burned cooling system. We recommend that you should get the filters cleaned and replaced in every few months.

Our experts can also help you with intense or chemical cleaning of these filters for better results. Let us know about the issue, and we will be there with the best possible solution for it.

If need to, we can provide aircon gas topping or troubleshoot to find the problems with your system.

Aircon Is Making More Noise Than Usual

If your aircon is making more noise than usual, it will not only sound unpleasant and disturbing, but it can also indicate a problem with some parts of the unit.

A lot of components interact with each other to form a single aircon unit. There are bearings, motors, fasteners, tubes, joints, fans, shafts, and many more.

All these components are under some stress and strain whenever the unit starts, runs and stops. At some point, they get unbalanced or break, which leads to unusual sounds.

This problem may aggravate further if it is not dealt with immediately and cause you a lot more hassle and money in getting it repaired. Therefore, even a little increase in the noise of the aircon should be inspected further.

Causes and Repair Options

There are a few reasons why an aircon might be making more noise than usual. Some of those causes and their respective solutions are discussed below:

Evaporator coils of the aircon are dirty

The evaporator is very identical to the condensing unit. The only difference is that this unit adds heat to the refrigerant. In this aircon part, there is a blower fan that produces air, which then absorbs energy from the evaporator coil, becomes cold and then gets circulated in the whole indoors. After this stage, the refrigerant again gets converted into vapours and passes to the compressor.  

If there is any accumulation in this part, the air quality of your home will decrease. In our experience of providing aircon servicing in Singapore, we have seen cases when the filth inside the evaporator turns the aircon system into a mould breeding ground, causing smells and clogging problems.

We advise our clients that they should get this part cleaned and repaired after every few months. We also suggest they get its filter replaced at least once in six months. In case the filth inside the evaporator unit is too much; we also provide chemical cleaning to deal with it and in severe cases, chemical overhaul.

Faulty Motor

One more reason for an aircon to be making extra noise could be a faulty motor. This problem should not be ignored as this can cause the compressor to break down. A professional technician might be able to repair a faulty motor or replace it if repairing is not possible.

Since an aircon consists of several parts, if even one of the parts becomes loosened, it will cause the aircon to make increased noise. The solution to this problem is to regularly service the aircon and inspect it so all the parts can be fixed properly in their places.

If you hear a screeching noise, it might be coming from the blower motor. Either it needs to be lubricated or its belt might need to be replaced. Keeping the unit running continuously in the presence of such a noise can lead to the motor crashing.

If the noise you hear resembles that of rattling or banging, it could be because of a problem with the motor or fan assembly. Again, keeping the aircon running in such a situation can further aggravate the problem. The aircon should immediately be shut down and get inspected by a professional.

If the noise seems to be coming from the blades of the fan or blower, there might be something stuck between them. Removing the outer cover and inspecting the fan blades for any obstruction can fix this issue.

When you hear the noise only when the compressor turns on, it can signal a problem with the relay or a failing motor. The aircon should be inspected by a technician to identify the issue and fix it.

Aircon Does Not Turn On

The most crucial part of an air conditioning system is its power source. If your aircon does not turn on, one of the following causes may have to be blamed:

Causes and Repair Options

Blown Fuse or Faulty Wiring

If the aircon does not turn on, one possible reason could be that its fuse may have blown. The solution is simple in this case: just replace it with a new fuse.

Another reason for the aircon not turning on is some problem with the wiring. This needs to be checked by an electrician to determine the exact problem and fix it.

Check the wiring for any sign of burning. If the wires are fine, we move on to the circuit breaker unit, which sometimes turns off due to a sudden power imbalance. The switch will stay at the position if there is no further power imbalance.

However, if the breaker keeps on tripping, it is a sign of a more significant problem. Tripping may happen due to a broken circuit breaker, blocked air vents, leakage, short circuit and more.

One probable reason for the aircon does not turn on is a faulty motor or compressor. Again, this needs to be inspected by a professional.

Damaged Compressor Motor

Another problem is that the motor dies. This could signal another problem with the fuse. The job of the fuse is to prevent the motor and compressor from overheating.

If the motor dies, this means that the fuse had become faulty and was not able to stop the motor from overheating. Replacing the fuse with a new one will prevent any future similar issues.

Like any other electro-mechanical system, the motors of aircon systems also come with capacitors. The small energy reservoir cell stabilizes the input voltage, regulate the pulse, and most of all provide a jump start to the motors. It is an essential part of the compressor motor, blower motor, and even the outdoor fan motor. 

Therefore, if one or two of them stop working while the remaining does their job correctly, the capacitor is the next likely culprit.

Damaged Capacitor

 If the capacitor wears out, it won’t be able to send signals to the motor to start and keep working. This problem can be solved by replacing the capacitor.

In this case, we use a meter to find the potential difference between the terminals of the capacitor. We also scan for physical damages such as splitting, leaking or bulging. Once we are sure of the problem, our team will fix the problem or replace the cell with a new one according to the damage.

Moreover, never try to handle the capacitor on your own. The capacitor stores current, enough for you to feel it even when the main switch is off.

Our expertise as a professional aircon repair and servicing firm in Singapore allows us to analyze the system very quickly and efficiently. Whether it’s the coil accumulation, dirty filter or a blocked vent, we will repair them in no time. Our team immediately will use tools to find the central cause of the problem and fix it.

Complete System Failure

When the volume of refrigerant in your aircon system decreases beyond a safety point, the cooling system undergoes uneven stress. Therefore, your aircon system starts to consume more power which soon leads to complete cooling system failure. In these scenarios, we recommend that you turn off the aircon system and let us fill its coolant.

Ignoring the aircon system during this stage will lead you to long term damages and sometimes a completely shut aircon system. 

Moreover, the lack of aircon maintenance and servicing will also contribute to health damages.

Helpful read: Common Misconceptions About Aircon System And Their Servicing

Severe Environmental Effects of Unclean Aircon And Refrigerant Leakages

The pollutant inside your air conditioner makes it very vulnerable to moulds depositing and breeding. These moulds reproduce and in no time grow to a scale where they fill the whole airflow of your aircon unit. They are also a leading contributor to smelly aircon systems and unhealthy indoor environment.

Another worst thing about a filthy and non-serviced aircon system is that it hides the symptoms of leaking refrigerant which is very harmful to the environment. In gaseous form, it enters the human body and causes problems like nausea, headaches, and sometimes asphyxiation.

In liquid form, this refrigerant can penetrate the deep layers of soil and pollutes the underground water. From here it gets absorbed by the plant roots, which are an energy source for a majority of animals, including humans.

Fortunately, you can prevent all these problems if you engage a professional. Our team has some advanced tools that can determine the level of the coolant and find the reason for its depletion. We can also help you to remove clogging in the coolant tubes and repair their leakages. Moreover, we can provide you with a gas top-up of both R22 and R410 refrigerants.

Factors That Can Affect Your Aircon Efficiency


A hot and humid climate like that of Singapore calls for extra care and maintenance to guarantee good aircon efficiency. This also means that you would require more air-conditioning units in a house and they would be running for longer periods of time to ensure a cool and comfortable temperature in your room.

When aircon run for long durations, they are more prone to accumulating dust especially in the outer units. To keep the inside temperature low, the air conditioner has to work constantly against the high temperature outside. This means that it will get affected by wear and tear faster as compared to an aircon which is installed in a relatively less hot climate. Only with regular servicing will your aircon be able to run smoothly and effectively year after year.


The kind of insulation your room provides also affects the efficiency of your aircon. If your room is able to resist heat, it will result in a better efficiency by the aircon as well. Good insulation helps the cold air to remain inside while still resisting the outside warm and summer air.

Using weather-resistant materials for doors, windows, and vents also results in increasing the aircon’s efficiency. The number of doors, windows, and vents also affect the way cold air remains inside a room. The more outlets there are in a room, the more there will be chances of cold air loss which will then have to be offset by your aircon.

Room Size

The size of a room also affects the efficiency of the aircon. A bigger room will require a bigger capacity air-conditioning unit otherwise it will not function properly.

If a low-capacity aircon is used in a big room, it will cause the aircon to work much harder in order to maintain the temperature. This will cause more wear and tear to the aircon in less amount of time resulting in more malfunctions and a drop in its efficiency.

Typically, during aircon installation, the experts will calculate the room size and determine the BTU of the aircon needed, where BTU is defined by the cooling power of the aircon unit.

Helpful read: Aircon BTU – The Meaning Behind the Acronym and Its Application

Poor Airflow

If your aircon is facing issues of poor airflow, it might not work properly. Poor airflow can be defined as some blockage which does not allow the aircon to breathe properly.

This can be due to a clogged air filter or a blocked condenser unit. In the presence of such a blockage, the aircon has to work harder to keep the room cold.

This not only further aggravates the problem and cause other malfunctions, but it also consumes a lot of energy. This is then manifested in the form of higher utility bills. A good servicing should be able to help increase the airflow of the aircon.

Clogged coils

Coils of the condenser are responsible for transferring the heat of the room outside while the air con continues to bring cold air inside. If these coils get clogged or a layer of dust forms on it, it affects the condenser’s efficiency.

It will not be able to take the hot air of the room outside as efficiently as it could so it will have to work much harder. This will again cause other parts of the air-conditioning to malfunction which can even lead to a system failure. Keeping the condenser coils clean and unclogged are essential to ensure the smooth functioning of your aircon.

Another factor relating to the condenser coils which can affect your aircon efficiency is frozen coils. The condenser coils need warm air flowing around them to be able to function properly.

If the airflow is restricted through a clogged air filter, this can cause the coil to become cold resulting in the formation of a layer of ice on the coils. This will stop the aircon from throwing in any cool air inside the room.

In such cases, you may need an aircon chemical cleaning or overhaul service to clean out the stubborn stains and blogs.

Duct Issues

If there is any leak, crack, or gaps in the ductwork of the aircon, it will negatively affect its efficiency. The gaps will not only prevent the cold air from reaching all parts of the room, but it will also allow hot air from the gaps to be mixed with the cold air.

This will cause the aircon to work harder to maintain its efficiency resulting in higher energy bills. This will cause the efficiency of the aircon to drop. The gaps will also result in more dirt buildup inside the ducts further decreasing the efficiency. These gaps and leaks in the ductwork may be caused by poor installation or rodents.

chemical cleaning or chemical overhaul service can help in removing the excess dirt and making the airflow more smooth.

Fan Issues

There are two fans inside your aircon system. One fan in the inner unit is responsible for blowing the cool air over the evaporator coil and into the room whereas the other fan in the outer unit is responsible for throwing the hot air from the room through the condenser coil and outside the house.

If any of these fans stop working either due to a worn-out belt, lack of lubrication, or dust buildup, it will affect the aircon’s efficiency. A faulty fan can result in poor airflow which will take out the toll on the condenser. It can even lead to a system failure if not addressed.

Thermostat Issues

Issues with the wrong setting of the thermostat can also affect the aircon’s efficiency in the long run. In the case of older units with a manual thermostat, it could easily malfunction.

You could apparently be setting the thermostat at one temperature whereas it might not be getting set at that temperature because of the malfunction.

In the case of modern digital thermostat settings, setting it on a lower value will push the aircon to its limits where its compressor might not be able to rest in between. This can affect the compressor and its efficiency.

Setting the thermostat to a reasonable temperature will not only allow the aircon to continue with its efficiency for longer periods but also help in conserving energy and bills.

Drain Issues

An air-conditioner works by expelling the moisture that it collects from the room and throwing it outside through a drain pipe. If this pipe does not drain properly, it can result in water leaking from the front unit.

If the pipe has leaks or cracks near or inside the wall, it can damage not only the walls but also the inner parts of the air conditioner. This can even result in the growth of mould which can completely rot the pipes inside the framework of the aircon.

The only solution in such a case would be to completely change the inner pipes which is a long and troublesome process. These are some of the factors that can cause the efficiency of your aircon to decrease. By having regular maintenance checks and servicing, you can ensure that your air-conditioning unit continues to work efficiently.

Helpful read: Wonder Why Your Aircon isn’t Blowing Cold Air? Here’s Why

Final Words

These are just a few of the problem; there are other non-common problems that you may come across.

However, before you run into trouble with the cooling system and start to blame it for everything, have a look around your place. Sometimes the customers call us for aircon repair while there is nothing wrong with the system. Instead, there is a leakage in the house or an external heating agent that’s causing the problem.  

In such cases, we usually use some incense sticks to find the air leaks, cover the window or roof glasses and make some changes to thermostat placement for improving the aircon system’s efficiency.

Whatever the problem with your aircon system,  you can always trust our services.

All the above-mentioned problems are some of the most common ones that you might encounter with your aircon.

It is always a good idea to call a professional to carry out aircon repair for you so you can be assured that the problem will be identified and fixed efficiently. LK Brothers is a professional aircon repair and servicing company that excels in providing high-quality service and repair solutions for all your aircon-related problems.