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The On And Off Cycles Of An Aircon Unit

One of the most vulnerable aircon unit components that often catch failure is the aircon unit compressor. It is necessary to find a solution for this certain aircon issue as early as possible for avoiding any future wear and tear to the entire aircon unit system.

The aircon unit compressor is responsible for moving the refrigerant between the evaporator and condenser coils, ensuring that the refrigerant changes to gas or liquid as needed. Therefore you can think of the compressor as the heart of the entire aircon unit and the refrigerant as the blood.

So to save the aircon unit from trouble, would it not be normal if the aircon unit compressor remains on for long? In humid conditions, sometimes you can turn on and off the air conditioner compressor. The humid and hot weather wouldn’t keep the compressor on and off for long, and you should know that something isn’t right here. It would be necessary to get the aircon issue fixed as early as possible. You can also identify all the possible aircon issues for troubleshooting them in the right way. 

Aircon Unit Cycles:

Short Cycle

The short cycle occurs when the blown cold air or warm air does not travel far and returns immediately. It happens when there is something near the vents that blocks the airflow.

Temperature is measured at the suction port of an aircon unit to determine if the set temperature has been reached. It immediately vents warm or cold air. As a result, the temperature sensor misperceives that the purpose has been accomplished and weakens or stops functioning. The compressor of your aircon unit turns on and off several times and each time it turns on the system gets a little bit of cool air. If the aircon unit is short-cycling you are causing your aircon unit to turn on and off several times. This is causing the entire aircon unit to use more energy to cool your home. Also, if the aircon unit continues to short-cycle, your compressor could fail.

Long Cycle

A long cycle means the aircon unit turns off less often and keeps running for a very long time. This happens when the temperature of the room is changing slowly. As a result, the aircon unit is on for a long time to meet the desired temperature.

The aircon unit will cool down the room for a little while, but if it has been running for a long time, it will start heating up and take a long time to cool down again. This means that the room’s temperature will fluctuate frequently and it will be hard to keep the temperature constant. A constant running of the compressor in an aircon unit can lead to higher energy bills, which is not ideal for daily use. A longer cycle causes the compressor to run non-stop, causing humidity and mold growth in the unit and increasing wear and tear on the aircon unit.

Pro 338 Reminder: When you notice an unusual performance with your aircon unit compressor than the usual, immediately call for a professional aircon servicing company. It is an aircon issue that needs to be addressed immediately to avoid some serious aircon issue or major breakdown.

Why should the aircon unit compressor cycle be turned on and off?

As the aircon unit functions for cooling down the air, the actual work is done by the compressor. With the compressor, the air is cooled down till it reaches the required temperature. In a humid climate, the aircon unit compressor would need to work hard to maintain the required temperature.

The cooler temperature you set, the harder the aircon unit compressor works for getting cooled down the air. The aircon unit compressor is turned on when it needs to cool air. After the required temperature is attained the aircon unit compressor cycle gets off until the air again gets hotter. Then it again cycles on and starts cooling air. This happens in a pattern depending on the weather in addition to other factors.

How often should an aircon unit be switched on and off?

It would be normal for an aircon unit compressor to frequently get switched on and off. Whenever the air is too hot, the aircon unit compressor cycles are used for cooling it down until the required temperature is achieved. The aircon unit’s cycle time is the time required for the compressor to work and cool down room temperature to the ideal temperature on the thermostat.

When you set the thermostat temperature to low compared to room temperature, the compressor stays for a long period. It needs to work for a significant period to cool the whole space. It also increases cycle time for reducing the room temperature.

Thus, when the temperature difference between the aircon thermostat and the room is high, the cycle time will be longer. When there is a decrease in temperature difference, the cycle time lessens as well.

No certain cycle is there for switching on/off the aircon compressor. As it has been mentioned, it would depend on the room temperature with the thermostat temperature difference. Also, this depends on the cooling capacity of the aircon unit, the area that requires cooling.

The aircon issue arises when the compressor has abnormal cycling off and on the pattern. This can either happen when the compressor doesn’t switch on at all, or it might frequently turn on and off itself without cooling for long. You can follow these patterns for understanding when something isn’t right with the aircon compressor. When you notice such abnormal compressor cycling, it requires attention and it would be better to call a professional aircon servicing company.

What to do when the aircon cycles are abnormally turned off and on?

As mentioned already, the compressor must cycle according to cooling capacities like the humidity, weather conditioners, and temperature to which it cools the air. All such factors also play a vital role in compressor cycle time.

However, if you’ve found the cycle time to be abnormal and the aircon compressor turns on and off within seconds, you’ll have to contact a professional aircon servicing company. For avoiding further damage, the compressor needs a quick fix.

Here are some reasons for abnormal aircon unit compressor cycle time:

Blocked condenser

When dirt particles block condensers in the aircon unit compressor, then the aircon unit doesn’t function in a normal way. It wouldn’t be able to cool down the heated and compressed refrigerant that passes through the condenser.

When putting a load on the compressor, you can make it overwork and it disrupts the standard cycle time.

Dirty Evaporator

Similar to the condenser, the evaporator unit can also get blocked with debris and dirt. It can hamper air drying and also impacts the compressor cooling effects. This makes the compressor work a lot to cool the temperature of the car and it automatically increases cycle time.

Low Refrigerant

When the amount of refrigerant in the compressor reservoir minimizes, it doesn’t function in a normal way. The compressor requires a sufficient amount of refrigerant for normal functioning and cooling the air.

When the refrigerant in the aircon unit reduces because of leakage or other reasons, the compressor has to work more for cooling down the air. It also increases cycle time. You’ll require a professional aircon servicing company for aircon repair and restoring the level of refrigerant.

Standard Cooling Cycles

How long must the compressor run in the system of an aircon unit cooling cycle? For conserving the power and providing the aircon unit a break, you can set the thermostat at the most comfortable temperature. For on/off cycles, it is recommended to aim for around 25°C. However, even at the high setting, a day with 37°C temperature forces longer cooling aircon cycles.

In mild weather, when the aircon unit doesn’t face more trouble in meeting the temperature setting, the compressor periodically cycles down. The least cooling cycle should be for around 15 minutes.

It shows how much time the air handler and compressor require for distributing cooling around the home. When shorter cycles are run in the compressor, mainly less than 10 minutes, then it would be short-cycling and this would require a professional aircon servicing company’s attention.


It’s always a good time to talk about the common issues that aircon units have. This way, you’ll be able to spot if there are problems with your unit or not and prepare for its replacement accordingly. If you require our aircon servicing services, Whatsapp us at +65 9222 4141 for a fast and transparent quote.

338 Aircon Servicing Singapore provides an extensive range of Aircon Services including Aircon Servicing, Aircon Repairs, Aircon Installation of the best aircon brands, Chemical Overhaul, Gas Top-up, Aircon Leaking Water, and Aircon Not Cold Fix, and more. We have a team of professional technicians who are equipped with vast knowledge and experience in the Aircon industry. 

We have over 15 years of experience in dealing with aircon works and have completed thousands of aircon works for both residential (Landed, Condo, and HDB) and commercial. We are a highly recommended Aircon Company in Singapore, with many delighted customers and reviews over the years on Google and Facebook.

WhatsApp us at +65 9222 4141 for a transparent quotation and honest pricing for all your aircon needs or Call us at +65 9222 4141. We offer a fast and efficient service to serve any of your aircon needs!  

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