Running, moving air, but not cold. The thermostat, the outdoor fan, the filter, and the one part you should never open.
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Air conditioning problems
A central air conditioner that runs but does not cool, or that ices over, is telling you something specific about airflow or refrigerant. And one part of the fix is never something to do yourself.
Why the outdoor unit matters as much as the indoor one
Central air conditioning splits its work between an indoor coil, which the furnace's blower moves air across. And an outdoor condenser unit, which rejects the heat that coil absorbed. A fault in either half can produce the same symptom indoors, warm air where cold air should be, which is why this section keeps pointing you outside to the condenser as well as at the filter.
Refrigerant handling is federally regulated in the United States: only a technician certified under EPA Section 608 may legally purchase or handle it. That single rule shapes what this section will and will not tell you to do yourself.
Air conditioning guides
Ice on the coil means restricted airflow or low refrigerant. And running it through the ice makes things worse.
Condensate that stopped draining. A blocked line, a thawing coil, a rusted pan or a dead pump. And where the water shows up tells you which.
Running a few minutes and shutting off is hitting a limit, not a setting. Airflow, an oversized system, the condenser outside, or the thermostat.
A plain air conditioner never makes heat. Work out what you own, then check the thermostat mode, filter and outdoor fan.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- ENERGY STAR. Energy Savings at Home: Heating & Cooling
- ENERGY STAR. Furnaces