The air conditioner has made home life more comfortable, which is why we homeowners take great care in maintaining it. However, even the most experienced homeowners would find themselves in frustrating situations when their air conditioner turns on and off in what is called short cycling.
This problem can happen with both indoor and outdoor units and is often caused by thermostat malfunctions, refrigerant issues, or clogged filters. In Singapore’s humid climate, short cycling can leave your home feeling hot and uncomfortable.
Find the 10 most common reasons why AC units malfunction, and how to fix them.
Causes of Aircon Short Cycling
Reason #1: Thermostat Issues
Placing your thermostat in a warmer or cooler place than the rest of the room such as on the spot where it gets direct sunlight or right under an air vent, can give you inaccurate readings. This can cause the aircon to short cycle as it tries to match the temperature setting.
How to Fix It?
- Relocate the thermostat to a central spot in your home, away from the heat sources and direct airflow.
- If you live in an HDB or condo in Singapore, make sure to place it in a hallway or shaded area.
Reason #2: Refrigerant Leak
Singapore’s tropical climate means aircon works extra hard, and over time, refrigerant leaks can develop. When refrigerant levels are low, the aircon may turn on and off repeatedly because the compressor struggles to maintain pressure. When the unit is off, the pressure builds up again, the compressor powers up, and the cycle continues.
How to Fix It?
- Check for signs of a refrigerant leak, most of our clients in Singapore experience hissing sounds or weak cooling when they have a refrigerant leak.
- If you suspect a leak, contact us at Luce Aircon Services to check your unit for any cracks or holes.
- Regularly servicing your aircon can prevent leaks.
Reason #3: Restricted Airflow
When airflow is restricted, the warm and cool air cannot properly circulate enough to cool down your room. The AC then becomes faulty and cannot perform as intended, causing the unit to short cycle. Airflow issues may be caused by clogged drain pipes, frozen compressor coils, dirty air filters, and more.
This issue is common in air conditioners located in older Singapore HDB flats where dust buildup happens faster due to ventilation limitations.
How to Fix It?
- Clean or replace air filters every month, especially if you live near high-traffic areas in Singapore where pollution can lead to faster clogging.
- Check and clear any obstructions in your air vents.
- If you have an HDB ceiling aircon, ensure proper ventilation in your room.
Reason #4: Dirty Air Filter, Evaporator Coils, or Condenser Coils
A dirty or clogged air filter, evaporator coil, or condenser coil can restrict airflow and cause problems with cooling the air. If your air conditioner turns on and shuts off repeatedly, it might be due to frozen condenser coils that get icy. The AC unit shuts off when the ice is thick, only to turn back on when the ice melts.
How to Fix It?
- Clean the air filter every two weeks.
- Book professional coil cleaning at least once every 6 months.
Reason #5: Electrical Problems and Capacitor Failure
With new and cleaned units, the issue may lie with the electrical wiring which can cause the air conditioner to short cycling. The internal circuit boards may be faulty, or there might be a misconnection in the wiring of your unit and thermostat.
Along with electrical problems, the capacitor may have been overloaded. A faulty capacitor cannot provide your AC unit with the initial power boost it needs to function properly.
How to Fix It?
- Check for burnt wiring or loose connections and call an electrician if needed.
- Use a surge protector to shield your AC from power surges, especially during Singapore's rainy season.
- If your capacitor is failing, immediately replace it with the help of a professional technician.
Reason #6: Compressor Failure
Compressor failure can sometimes be caused by a refrigerant leak and is damaging to your air conditioner. Your AC compressor may be starting to overheat, break down, or malfunction, which is causing your unit to shut off repeatedly. Faulty air conditioner compressors are one of the most common problems amongst Singapore homeowners, as some might let the aircon run almost 24/7 due to Singapore's constant hot and humid weather.
How to Fix It?
- Turn off the AC and let it cool for a few hours before turning it back on.
- If the problem persists, book a professional AC servicing to check for internal wear and tear.
- Consider upgrading to an inverter aircon, this type of aircon is best to handle Singapore’s climate more efficiently.
Reason #7: Aircon Overheating
Aircon overheating is very common to happen during Singapore’s hottest months. Many people run their AC non-stop in order to stay comfortable despite the blasting sun. Although this can be great for your comfort, but this can be damaging to your aircon—and eventually cause it to overheat and start short cycling.
How to Fix It?
- Give aircon breaks between long hours of use.
- During Singapore's hottest month, use ceiling fans or dehumidifiers to reduce heat and humidity indoors.
Reason #8: Oversized Air Conditioner
Is this problem happening to your newly installed unit? It may not be a problem with the components of your air conditioner at all, but rather due to an oversized air conditioner unit. A higher horsepower may cool down your space a lot faster, but it can also cause AC to keep turning on and off. Your air conditioner might be too big and can quickly cools down a room, and then shuts off once it reaches the desired temperature only to turn back on when the room gets warm.
How to Fix It?
- For a typical Singapore HDB bedroom, a 9000 BTU unit is ideal. If you have larger spaces, it’s best to consult an aircon specialist.
- Consider using a multi-split system, which offers more precise cooling for multiple rooms.
Reason #9: Energy Saver Feature
The energy-saving feature can sometimes be the simple cause of what you might think is short cycling! Some aircon models come with an energy-saving mode, which can turn the unit off once the room reaches the set temperature. If you notice your aircon keeps turning on and off by itself, this feature might be enabled.
How to Fix It?
- Check your remote control settings and disable energy-saving mode if needed.
- For smart aircons, you can adjust the settings via your mobile app.
Reason #10: Faulty Safety Switch
Modern aircon has safety switches that automatically shut down the unit if they detect an issue, such as overheating or power fluctuations. This can be triggered by electrical issues or a dirty unit.
How to Fix It?
- Reset the safety switch (check your aircon’s manual for instructions).
- If the issue continues, get a licensed AC technician in Singapore such as from Luce to inspect it ASAP.
How to Prevent Short Cycling?
When your air conditioner keeps turning on and off repeatedly, it won’t only make your home uncomfortable but also increases electricity bills and shortens the lifespan of your AC unit. Preventing short cycling is important to keep your air conditioner running efficiently, especially in Singapore’s hot and humid climate.
Proper Installation and Placement
One of the biggest reasons why an aircon turns on and off by itself is due to improper installation. If the AC is too powerful for the room, installed in a poor location, or not fitted correctly, short cycling can occur. It’s important to choose the right size aircon for a room, for example, a 9000 BTU unit is typically suitable for small HDB or condo bedrooms, while larger rooms might need 12,000 BTU or more.
Regular Maintenance
We always tell our clients that regular maintenance is the most effective way to prevent AC from turning on and off repeatedly. Especially with Singapore’s climate, where high humidity, dust, and air pollution—can quickly lead to clogged filters and dirty causes which is usually the main cause of short cycling. For air conditioners in HDBs, condos, or landed houses in Singapore we recommend getting it service at the very least once in 3 months.
If you use the AC frequently or live in high-dust areas like industrial zones such as Tuas and Jurong—we recommend to get the aircon cleaned every 1-2 months.
Immediate Repairs and Replacement for Faulty Components
We often have clients who ignore small problems and it eventually leads to bigger issues. That’s why if you notice unusual noises coming from the air con, weak cooling, or AC suddenly short cycling—it’s best to act fast before your unit gets worse. Book an aircon inspection as soon as possible!
Turn to the Aircon Repair Experts
Luce consists of seasoned professionals who will be with you through your entire AC journey, from installation and cleaning, to maintenance and repair. As a trusted aircon servicing company in Singapore, we cater to all types of aircon units across different brands.
Call or drop us a message today to book an appointment.
