AC not cooling enough? 9 Possible Reasons explained

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During summers the outside temperature and humidity become unbearable.


Only an air conditioner can save us by providing its cool breeze.

Especially at night time!!!

Imagine sleeping at night without an AC in the summers. This is next to impossible for a few of us.

Till now your AC was working all fine.

But from few days you start to notice, it is not cooling enough.

Or it has stopped cooling at all. You are now observing hot air blown from the AC instead of cool.

What could be the possible reasons?

Let’s find out.

“There are several reasons for poor cooling of your AC. The best way to find and solve this problem is to consult an expert technician or an AC service company.”

Below you will find the possible reasons that hinders your AC from working at its full potential. This goes for both window and split AC.

1) Low Refrigerant Level

low refrigerant gas level

Most Common Reason

An air conditioner works on the mechanism of “refrigeration” just like a fridge.

In this refrigeration process, the refrigerant gas is used.

If there is low or no refrigerant present inside the coiling then the AC will fail to work.

The only possible reason for low refrigerant is leakage otherwise it cannot get low on its on.

This occurs when there is holes in the coiling.

If there are no holes in the coiling, there will be no leakage and the refrigerant level will never go down.

From my experience, I have seen the AC service technicians are sometimes responsible for such a fate. It happens at the time of AC servicing. This is not always true for every technician but I have generally observed the same. 

This can also happen due to corrosion of coiling overtime.

You will need to call an AC technician for finding out the “low refrigerant” issue. 

One way to find it out yourself is running the AC and if the compressor starts then after a few minutes check the indoor coiling(evaporator). 

If ice starts to appear on the coils, this indicates a low gas level. 

In the case of a low refrigerant level, you will need to “refill” your AC.

2) Damaged MCB

aircon mcb

MCB is a switch often used directly with the air conditioner. This is used to protect the AC from overload, power surge, or short circuit.

Too old ACs that use high amperage current or areas with unstable power supply can lead this switch to damage or burn.

With damaged MCB your AC may not start and if it starts it may shut frequently.

3) Faulty PCB or Internal circuitry

The internal circuitry of an AC includes the PCB, capacitors, etc 

PCB controls the operation of the AC, if it gets damaged your AC may not work properly leading to inefficient cooling or even no cooling.

If your aircon is under warranty then it is easy to get PCB replaced otherwise getting a new PCB is difficult.

4) Dirty Filters

window ac dirty filter

Your room air gets cool by coming in contact with AC’s evaporator coils.

Your AC indoor unit consists of air filters used to protect the evaporator coiling from dust.

With time these filters get dirty.

A dirty filter clogged with dust particles disrupts the passage of air.

Due to poor air circulation between the room air and the AC, the cooling becomes inefficient. 

You need to clean the air filters on a monthly basis. This is easy to do and can be done at home.

If living in polluted cities then you will need to clean the filters every week.

5) Dirt buildup on the indoor or outdoor coiling

dirt buildup on the evaporator

Like air filters.

AC’s indoor and outdoor units both get dirty with time especially the “condenser”(outdoor unit). 

This reduces the cooling efficiency thus leading to poor cooling of your home. 

Dirt buildup also reduces the lifespan of the appliance.

Make sure to service your AC every year.

5) Clogged Drain hose

An air conditioner can also dehumidify your room. 

The moisture from the room gets collected in the AC which then gets drained out from the drain pipe.

A drain hose clogged with dirt can lead to water leakage problems or even shutting down of the AC.

6) Damaged Compressor

“Compressor” is the main component of any Air Conditioner.

This drives the refrigeration mechanism or cooling of your home.

The compressor is a motor that compresses the refrigerant and circulates the refrigerant through the evaporator and condenser coils. 

A damaged compressor may not work properly leading to failure of the AC.

AC manufacturers give a warranty on compressors of several years like 5 to 10 years.

If your compressor is under the warranty period you can get your compressor replaced.

7) AC too old

old rusted aircon outdoor unit

With time efficiency of most the appliances go down.

Though air conditioners can last for several years.

But with time its cooling efficiency and power efficiency start to deteriorate leading to inefficient cooling.

Such ACs consume more power and bring higher electricity bills.

If your AC is too old like 7-10 years, you should consider selling it for a new one.

Check this power consumption calcualtor, using this you can calculate electricity bills for any AC.

8) Outdoor Unit in direct sunlight

hitachi aircon outdoor unit in direct sunlight

Your AC works harder when direct sunlight falls on the outdoor unit.

This also reduces the life of the condenser unit.

An AC cools a room by extracting heat from it. This heat goes towards the outdoor unit which needs to be discharged in the outdoor environment. 

Direct sunlight heats the condenser unit way higher making the heat exchange harder.

Placing the outdoor unit in a shade where sunlight is not direct is helpful.

9) Undersized AC

Undersized AC means that the cooling capacity of an AC is lower than required.

This capacity is measured in terms of tonnage.

You need to choose the right tonnage AC according to the room requirement.

With a bigger room size, you need higher tonnage AC.

An undersized AC works on its 100% cooling capacity but it may never reach the desired room temperature.

Further Reading

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