An air conditioner running but not cooling properly usually points to weak airflow or a refrigerant problem. The most common cause is a clogged air filter or a dirty outdoor condenser coil that can’t dump heat.
Other culprits include a frozen evaporator coil, thermostat misreadings, blocked supply/return vents, or duct leaks that spill cold air into the attic instead of your rooms. Low refrigerant from a leak will let the system run but removes far less heat, and prolonged operation can overheat the compressor. A half-clogged return filter can drop airflow enough to ice the coil even when the blower sounds normal. Our technicians see this often in homes we service around Cedar Park during peak heat.
Quick checks you can do before a service visit:
- Replace a dirty filter and open closed vents
- Rinse debris from the outdoor unit’s fins (power off first)
- Set thermostat to Cool, Fan Auto, and verify temperature drop
- Clear a full condensate drain if the air handler stopped
If you see ice on the refrigerant lines, turn the AC off and run the fan to thaw before restarting.
Updated: 2026-05-16
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