Air Conditioner Not Cooling: Top Causes and Solutions
When summer heatwaves hit, discovering that your air conditioner is running but blowing warm or room-temperature air is deeply frustrating. In most instances, the problem is caused by restricted airflow, an electrical start failure, or a refrigerant gas leak.
1. Extremely Clogged Indoor Air Filters
Dust-choked filters restrict airflow across the evaporator coil. Without sufficient warm air passing over the coil, the refrigerant cannot evaporate properly, causing the indoor coil to ice over and halting cooling entirely.
Solution: Open the indoor split cover, pull out the two mesh filters, wash them under lukewarm tap water, let them dry completely, and reinstall them.
2. Refrigerant Gas Leak in Copper Lines
Air conditioners operate in a sealed, closed-loop refrigerant circuit; refrigerant gas is NOT consumed during normal operation. If gas is low, there is an active micro-leak at a flared brass joint, valve, or corroded pipe.
Symptoms: The thin copper pipe on the outdoor compressor frosts over, the indoor unit blows neutral air, and cooling performance degrades steadily over days.
3. Defective Outdoor Compressor Start Capacitor
The outdoor fan may spin, but if the start/run capacitor has failed due to heat or age, the hermetic compressor cannot start. You will hear a brief hum every few minutes followed by silence.
Solution: A certified HVAC technician can test and replace the capacitor in 20 minutes.
4. Blocked Outdoor Condenser Coil
If the outdoor unit (on your balcony, rooftop, or facade) is covered in dust, leaves, or bird debris, heat cannot dissipate into the exterior air, causing the compressor to trip on thermal overload.
FAQ
How often does an air conditioner need a gas recharge?
Never in a properly sealed system. If an AC unit requires gas, the technician must locate and seal the leak before recharging with R32 or R410A refrigerant.
How much does it cost to fix an AC refrigerant leak and recharge?
Leak detection, nitrogen pressure testing, flare repair, vacuuming, and an official R32/R410A recharge typically cost between €150 and €280.