When an air conditioner runs but the house never gets cool, the cause is often something simple, though some problems need a licensed technician. Here is how to narrow it down safely before you call for service.
Start with the thermostat
It sounds basic, but confirm the thermostat is set to cool, the temperature is set below the room temperature, and the fan is on auto rather than running constantly. Fresh batteries and the correct mode resolve more no-cooling calls than people expect.
A dirty filter or blocked airflow
A clogged filter chokes the airflow the system needs to move heat. The result is weak cooling and, eventually, a frozen coil. Check the filter first, and make sure supply and return vents are open and unobstructed by furniture or rugs.
A frozen evaporator coil
If you see ice on the indoor coil or the refrigerant line, the system is iced up, usually from restricted airflow or low refrigerant. Turn the cooling off and let it run on fan only to thaw, then replace a dirty filter. If it ices again, it needs a technician.
A dirty or blocked outdoor unit
The outdoor condenser releases the heat your system pulls from inside. If it is packed with leaves, grass or debris, or crowded by plants, it cannot shed heat and cooling suffers. Keep the area around it clear and the fins clean.
Low refrigerant and when to call a professional
If the basics check out and the system still will not cool, the cause may be low refrigerant, a failing compressor or an electrical fault. Refrigerant is part of a sealed system and is licensed work, so it should never be topped up as a do-it-yourself task. Low refrigerant also signals a leak that needs to be found and repaired, not just refilled.
Frequently asked questions
Why is my AC running but not cooling?
Common causes are a wrong thermostat setting, a dirty filter, a frozen coil, a blocked outdoor unit, or low refrigerant. Work through the simple checks first, then call a professional.
Can I add refrigerant to my air conditioner myself?
No. Refrigerant is part of a sealed system and is licensed work. Low refrigerant usually means a leak that must be found and repaired, not simply topped up.
Why does my air conditioner keep freezing up?
Icing is usually caused by restricted airflow or low refrigerant. Turn the cooling off to thaw it, replace a dirty filter, and if it freezes again have a technician inspect it.
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