The air conditioner compressor is the heart of your cooling system. Located in the outdoor unit, the compressor processes the refrigerant, enabling it to absorb heat and release cool air into your space. When the compressor overheats or malfunctions, the aircon may struggle to cool your home effectively.
Given Singapore's sweltering weather, ensuring the compressor is in top condition is crucial. Thus, any issues on the compressor should be addressed immediately by a certified technician to prevent further damage.
8 Reasons Why AC Compressor Overheats and How to Fix Them
Cause #1: Damaged or Dirty Air Filter
Damaged or dirty air filters restrict the airflow around the unit, causing the warm air to get trapped inside. The air conditioner would have trouble getting air through a dirty or damaged air filter, which forces the unit to work harder. These can cause the compressor to overheat as it works harder to circulate refrigerant with the restricted airflow.
Troubleshooting Tip
Check the air filter regularly and clean or replace it every 1–3 months. Taking care of the air filter is very important, especially in Singapore’s humid climate—where dust buildup is common.
Cause #2: High Head Pressure
Similarly, dirty condenser coils in the air conditioner's outside unit may get clogged as dirt and debris pile up through the vents. Dirty coils cause high head pressure, which may make your compressor overheat as the cooling system fails to let the warm air out of the unit.
Ambient temperatures during extremely hot summer months in Singapore can also contribute to overheating. However, the most common reason for high pressure is a dirty coil.
Troubleshooting Tip
As high head pressure often occurs due to a dirty condenser coil, it’s important to clean the condenser coils to remove dirt and debris. Additionally, also ensure the outdoor unit is properly ventilated and not blocked.
Cause #3: Low Refrigerant Levels
When there's not enough coolant for the compressor to circulate, it can start to grind the AC system, which causes the mechanisms to overheat. Low refrigerant levels usually lead to serious problems, like leaking water, frozen AC coils, and even burnt smells. That burnt smell is the compressor overheating.
Troubleshooting Tip
Low refrigerant charge is often caused by a leak in the refrigerant pipes. In this case, it is best to contact one of our Luce technicians to find the leak and repair it. The technician would add a neon dye to the refrigerant to follow the path to the leak and repair the leak immediately before it damages your unit further.
Check out all the signs your AC needs a Freon recharge!
Cause #4: Inadequate Air Conditioner Size
Not all air conditioning units are the same, and the main difference with various models is the efficiency in their cooling capacity. The general rule is that the larger the area you need to cool, the stronger the air conditioning system is required to properly cool the space.
An air conditioner that is too small or weak to cool the room to the desired temperature will force the system to work harder to achieve the temperature set on the thermostat. This causes an overheating compressor.
Troubleshooting Tip
Verify that the AC unit is appropriately sized for the room or building. If the unit is undersized, consider upgrading to a more powerful model suitable for the space.
Cause #5: High Voltage Surge
A surge of high voltage may be rare in your area, but it is a probable cause of an overheating compressor. The high voltage may cause your cooling system to trip a circuit, and may also cause the compressor to overheat. You may notice a burning or exhaust smell coming from your unit when this happens, you should unplug the unit immediately for your safety.
Troubleshooting Tip
Power fluctuations or sudden voltage spikes can cause electrical stress on the compressor, leading to overheating. To troubleshoot this issue, you can use a voltage stabilizer or surge protector to safeguard the AC unit. If the unit has experienced an electrical surge, have a technician inspect the compressor for damage.
Cause #6: The Compressor Doesn’t Have Enough Ventilation
Proper ventilation is crucial for an AC compressor to function efficiently. In many Singaporean homes, especially in HDB flats and condominiums, outdoor AC compressor units are often installed in tight spaces such as service yards or balcony corners. If the unit is placed too close to walls or surrounded by clutter, heat cannot dissipate properly causing the compressor to work harder.
Additionally, Singapore’s environment exposes outdoor AC units to dust, fallen leaves, and even small animals that can obstruct airflow. Without sufficient ventilation, heat builds up within the compressor, leading to the air conditioner compressor overheating.
Troubleshooting Tip
Regularly clean around the unit to remove any debris that could block airflow, and ensure the outdoor unit has at least 2–3 feet of clearance on all sides.
Cause #7: There Are Old or Broken AC Parts
An air conditing system comprises multiple components that need to work together efficiently. In older air conditioners, parts such as capacitors, cooling fans, and refrigerant lines can deteriorate due to wear and tear.
When a capacitor weakens, it may struggle to provide the necessary power for the compressor to start properly, leading to AC compressor overheating symptoms. In Singapore, where air conditioners run almost daily, the wear and tear on these components occur much faster.
Troubleshooting Tip
Schedule routine AC servicing to inspect and replace worn-out parts before they cause serious damage. To prevent this issue from being overlooked, once in a while, you should listen for unusual noises or weak airflow as this may be an early sign of failing components.
Cause #8: Eroded Oil
Lubrication is essential for keeping the moving parts of an AC compressor running smoothly. Over time, however, the oil inside the compressor can degrade due to heat exposure. When this happens, the lubricant loses its effectiveness, increasing friction within the compressor and leading to compressor overheating AC issues. One clear sign of eroded oil is a burnt oil odor coming from the compressor unit.
We often find this issue in some of our clients due to Singapore’s climate, where high humidity can accelerate oil degradation. If left unaddressed, a poorly lubricated compressor will eventually seize up, resulting in a complete system failure that requires costly repairs or replacement.
Troubleshooting Tip
Regular maintenance prevents soil erosion and keeps the compressor running smoothly. This is because a professional technician can check the compressor oil and replace it if necessary.
Got Aircon Problems?
For any electrical problem, or issues with the internal parts of your air conditioner, contact our technicians at Luce Aircon. With decades of combined experience in cleaning, maintaining, diagnosing, and repairing air conditioners across Singapore, our HVAC professionals are sure to find the root of the cause of your AC unit, and keep the unit in tip-top condition!
Schedule a consultation with us today, and we'll do a thorough checkup of your aircon unit!
Check out our article on ac compressor not working but fan is running!
