10 Common Problems When Air Conditioner Operation

Air conditioner working

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Air conditioner is very common to use now, but sometimes has issues when using it, bring us lots of trouble.

What are the problems? How to solve them? Let us give you the explanation.

Air Conditioner Working Performance Is not Good

1. Filter is dirty or blocked

Poor air permeability of the filter will definitely lose a certain amount of cooling capacity. We advise cleaning the filter every 2 weeks to keep the air conditioner good performance.

Method: You can use a high-pressure water gun or rinse directly at the faucet.
After natural drying or high-temperature drying, install the filter again and switch on the A/C.

2. Setting temperature issue

If setting temperature is too low or too high, the compressor needs to work longer to achieve the temperature needed, so you will feel the A/C performs badly.

Method: Set the temperature at normal level, like 25-26°C, and after 15-20 minutes, down (in summer) or up (in winter) 2°C, finally get to your comfortable temperature.

This way will minimize the damage to your compressor or A/C main parts (electric board, fan motor), meanwhile can save part of the energy power.

3. Vertical/Horizontal air blade options are wrong

When air conditioner works, the electric board has selected the best direction of the air blade according to the working mode, using air convection to achieve the best overall effect.

Method: We recommend referring to the manual according to different modes, choosing a different direction of the air blade, or by the electric board’s self-programmed operation.

4. Incorrect selection of the wind speed for indoor unit

If wind speed is too small, the cooling mode will lead to low air temperature, so that the air outlet in the case of large temperature freezing, while the airflow is small, can’t effectively bring out the cold air in the indoor unit; When heating, the wind speed is small, but the air outlet temperature is high, so room can’t get hot in time.

Method: When you want to cool or heat quickly, adjust the air volume to a larger mode. Don’t set the temperature too low or too high at that time. When you can obviously feel the room is cold or hot, then according to your own requirements increase or decrease the set temperature.

Air conditioning

5. The compressor has a lower capacity

Some manufacturers use a lower-capacity compressor to claim higher capacity. For example, they use 12000btu to cheat as 18000btu. So your clients use “18000btu” at the space appropriately for real 18000btu, but the real capacity is 12000btu, the performance is not good indeed.

How to verify?

Method: You can google the series number (see below ↓ ), 9000btu≈2.5kw,12000btu≈3.5kw, 18000btu≈5kw,24000btu≈7kw,etc

(different compressor factory has a different value, but The difference is no more than 5% normally.)

Air conditioner compressor

6. Lack of refrigerant

Compressor needs enough refrigerant to run the whole air conditioner system, if below the average level, the refrigerant can’t effectively meet the cooling or heating needs of the entire system, so the effect you want can’t be achieved.

Method: You should check the volume of refrigerant every 1-2 years, a professional service company can help you.

Air Conditioner Is Too Noisy 

1. The air conditioning panel is loose

After a long time use, its panel will be easy to become loose for various reasons, thus, the vibration generated by the air conditioner in constant operation will make the panels rub against each other and cause mechanical noise.

Method: When heard the noisy of air conditioner, close to the panel to listen and watch carefully, you can easily feel the vibration and jitter, if not, it isn’t the cause of the panel.

2. Compressor running issue

Compressor is generally installed outside the room, and compressor is one of the sources of air-conditioning noise. At working, will produce a certain noise. The base of the compressor uses a spring vibration-proof structure. Before delivered, in order to avoid bumps in transportation and compressor rocking damage to the refrigeration system, often tighten the base nut to make the vibration spring compressed to the minimum.

Spring vibration-proof part

Before installing the air conditioner, the end-user should first pull out the chassis and relax the nut, so that the spring can play a role in avoiding vibration and reducing its vibration and noise during the operation of the compressor.

There are also a small number of compressor internal parts hit the shell, operation, issued intermittent metal percussion sound, encounter this kind of fault, can only open the shell to repair.

Another situation: the compressor bumped the auxiliary copper tube when working. You must keep their space when working, of course, you should find a skilled person or engineer to do that.

The last possibility: compressor has a QUALITY ISSUE. Some factories use unqualified compressors to cheat. Some unqualified compressors are long-time stocked (outlet is blocked),  some other unqualified compressors are second-hand.

3. Poor installation of internal fan or blade

If the AC installation is unreasonable, there will be lots of noise.

The installer is not professional, the position is not horizontal, or there is something stuck in it.

If the installation is unstable, when the outdoor unit is running, the indoor unit connected with the copper tube is affected by the compressor because of its instability, resulting in resonance.

As a result, noise is generated.

Method: To avoid these problems, you must find a professional installer, or ask your air conditioner supplier for a recommendation.

4. The sound insulation of the room is not good

The walls of the room are made of hollow bricks, and even if the start-up sound of the external unit is normal, it can also be transmitted to the room, then you will feel the sound is loud.

Each customer has different feelings about the sound. Of course, the normal sound of the internal unit is the sound of the air supply, which must be smaller than the fan.


1) Close doors and windows to increase the airtightness of the room, which can reduce indoor noise.

2) Turn the fan speed to a lower level, or whatever you can tolerate.

Has Peculiar Smell When The Air Conditioner Is Running

After long time use, the indoor filter screen and the interior of the copper coil, aluminum fins, cross fan, fan motor will accumulate dust, which will produce a peculiar smell and float into the air with the air conditioner on.

After the air conditioner is cooling or heating, there is moisture inside. When the air conditioner is turned off, the internal moisture is easy to produce mold, which is moldy.

Method: Use dehumidification function of the air conditioner, to get rid of the moisture inside the system.

Air Conditioner Leaks Water

1. Installation leads to air conditioning leakage

Install an air conditioner with an unqualified tilt that will leak due to the accumulation of moisture. During the installation, the wall hole is too high, resulting in poor drainage of the drainage pipe, so the water plate of the indoor unit is full of water, and the indoor unit will also leak.

Method: No angle tilt when installation, don’t hang up the indoor unit so high (2.5-3m normally)

Water leakage

2. In terms of use, it leads to air conditioning leakage

1) Dirty blocking

Means dust doesn’t clean in time and accumulates in the pipeline, filters, aluminum fins, etc resulting in poor drainage.

2) The drainage pipe is moved or knotted.

3) The drainage pipe (used for a long time) cracked due to plastic aging.

4) If the heat exchanger is covered with dust, the temperature of the heat exchange is uneven, and water droplets are produced in the middle of the heat exchanger, which will fall outside the water plate and drop into the room. Or the lack of refrigerant in the air-conditioning system will cause the indoor machine to freeze, and the water droplets formed by ice melting do not drop directly into the water plate but drop to room ground.

Method: Carefully check to find the reasons like the above, then take action accordingly.

Air Conditioner Can’t Switch On

1. The fuse in the special circuit of the air conditioner is blown, or the contact of the power switch is poor.

2. The power supply is so low. It is difficult to start the refrigeration compressor in the air conditioner when the voltage is less than 15% of the single-phase normal voltage (220V), that is187V, or less.

3. When the current of the compressor and fan motor is too large, the overload protection relay is operated and the power supply is cut off.

4. Whole system has an issue, the main parts ( electric board, motor, compressor) are broken. For this situation, you need to find a skilled service company to make inspections and repairs.

5. Ambient temperature is too high or too low

When the ambient temperature is lower than -10ºC or higher than +45ºC (for T1 compressor) or higher than +55ºC (for T3 compressor), the compressor will stop working, causing the whole air conditioner system failing to work.

Abnormal Sound When The Air Conditioner Starts Up

Air conditioner panel is made of thin plastic, which is light in weight, but because of the frequent change of temperature, will bring thermal expansion and cold contraction, resulting in abnormal sound. 10-15 minutes after starting up, the sound will disappear.

Air Conditioner Can’t Operate By Remote Control

If no lack of battery or the battery is not dying, thus the remote control is broken, or the indoor unit electric control board is broken (Because infrared of the remote control needs to transmit signal to the electric control board for remote purpose).

Remote control for air conditioner

Remote control to match indoor electric board

Air Conditioner Automatically Jumps

1. Too much or too little refrigerant, resulting in compressor protection trip.

2. Air conditioning system is blocked.

3. The outdoor ambient temperature exceeds the normal working range of the air conditioner.

If you use T1 compressor (maximum can stand +45°C) in a very hot area where is more than +45°C, the air conditioner will jump absolutely. You should use T3 compressor (maximum can stand +55°C) in there.

4. The heat exchangers and filters of air conditioners are too dirty, which affects the energy exchange of air conditioners.

5. Power supply voltage exceeds the normal working range of the air conditioner.

6. Outdoor fan motor, fan motor capacitor, indoor and outdoor fan failure.

7. The outdoor temperature sensor is damaged.

Method: Contact Us for help, or your local service company for inspection and maintenance.

Air Conditioner Compressor Frequently Switch On/Off

First of all, only the fixed-frequency (non-inverter) air conditioner will switch on/off frequently. This is normal because it needs to maintain the temperature accurately at the set temperature.

If the temperature difference between the set temperature and the room temperature is too small, it will aggravate the frequent startup of the non-inverter air conditioner. In addition, if there are wind-shielding objects around the indoor and outdoor units, it will also affect heat dissipation and cause the air conditioner to switch on/off frequently.

But inverter air conditioner will run at a low speed after reaching the set value to maintain the temperature unchanged, which can be said to be a “non-stop operation”.

Air Conditioner Stop Before Reaching The Set Temperature

The working time of air-conditioning compressor is limited.

Normally, it should stop until it drops to the specified temperature. However, if the ambient temperature is too high or the set temperature of indoor unit is too low, the compressor will take a rest after working for a period of time, even if the temperature is not lowered to the set temperature, this is the self-protection of the compressor itself: shutdown and cooling.

If your air-conditioning compressor has short working hours and long intervals, it is likely that the compressor is faulty or aging, then needs to be repaired or replaced.


When your air conditioner has some operating problems or malfunctions, you can compare the above items.

Maybe you can solve it by yourself without the help of maintenance staff, which can save some money,why not?

Any comments?

Welcome leave a message or repost.

About Author

Vic Cheung
Vic Cheung

I start working in HVAC field since 2008, main products included: air conditioning, cold room refrigeration system, chiller, commercial dehydrator, dehumidifier, heat pump, and all accessories. Since joined China Speedway Group in 2012, I worked in here more than 10 years, as the general manager of export department, we have established 50+ agent in different countries and areas.
As our experience and strong technical support, we can solve your issue once you have, and our chief engineer has worked in HVAC field since 1997. I am so proud of our knowlege is more and more popular not only for engineer, and for HVAC business new comer, DIY lovers. Hope you are enjoying our articles, if any question or comments just welcome to send me marketing at cn-beyond.com

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