When your AC is running but pushing warm air through the vents, it usually means one of four things. Here's how to narrow it down and what to do next.
If refrigerant is low, the system can't absorb heat from your home's air. You'll often see ice on the copper lines outside or hear hissing near the indoor coil. Refrigerant doesn't get 'used up' — if it's low, there's a leak. The leak must be found and sealed before recharging, or the new refrigerant will leak right back out.
A dirty filter, blocked vents, or low refrigerant can cause the indoor coil to freeze solid. Once frozen, the system can't transfer heat — so air blows warm. Running an air conditioner in this state can send liquid refrigerant back to the compressor, the most expensive component in the system. The ice is a symptom: the airflow restriction or refrigerant loss underneath it is what needs to be found.
The capacitor is a small cylinder that gives the compressor and fan motors the kick they need to start. If it fails, the outdoor fan may spin but the compressor doesn't engage — meaning no cooling happens.
Sometimes the fault is the thermostat rather than the air conditioner — set to 'fan only' instead of 'cool', left in heat mode, or with dead batteries. Tell us what the thermostat is set to and what it is reading when you call, and we can often narrow it down before we arrive.
Walk outside and check — is the outdoor unit running? If not, it could be a tripped breaker, blown fuse, or failed contactor. The indoor blower can still push air (warm), but without the outdoor unit, there's no cooling.
The more you can describe, the better the chance we arrive with the right part already on the truck. It helps to know:
If the air from the vents is still warm — or if you find ice on the refrigerant lines, hear hissing, or smell burning — call us right away. Running an air conditioner that isn't cooling puts continuous strain on the compressor, and that is the part you least want to lose.
SAVA is a family-owned, EPA Section 608 Certified HVAC company serving Chicago and North Shore suburbs. We diagnose the exact fault before any work begins, carry common parts for same-day repairs, and give honest repair-versus-replace guidance. Learn more about our AC repair service or emergency AC repair.
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