Field-informed guidance from Dustin Engelking, owner and HVAC technician at Empire Air.
Start with the safe homeowner checks
Confirm the thermostat is set to Cool and below the indoor temperature. Check whether the display is working and whether the indoor blower is moving air.
- Check that the filter is clean and installed correctly
- Make sure supply registers and return grilles are open
- Check the AC breaker once; do not repeatedly reset it
- Look for ice, standing water, unusual noise, or a burning smell
Common reasons an AC runs without cooling
Restricted airflow can make the evaporator coil too cold and may lead to icing. A failed capacitor, contactor, fan motor, control, or compressor can keep part of the system from operating. Dirty coils and duct problems can also reduce performance.
Low refrigerant is not normal wear. Refrigerant moves through a sealed system, so a low charge usually means a leak or a previous service issue. Pressure readings alone are not enough; temperatures, airflow, equipment data, and refrigerant measurements need to be evaluated together.
When to shut the system off
Turn cooling off if the refrigerant line or indoor coil is frozen, water is overflowing, the breaker trips again, or you notice smoke, sparking, or a strong electrical odor. Continuing to run a system with a serious airflow or electrical problem can create more damage.
- Leave the indoor fan on only if it can safely help thaw a frozen coil
- Never bypass a switch or safety control
- Keep water away from electrical equipment
- Call promptly if the home contains vulnerable occupants or unsafe indoor temperatures
COMMON QUESTIONS