Warm air, weak airflow and ice can have several causes. A thermostat or filter check may resolve a simple problem, while persistent icing or poor cooling needs an air conditioning technician.

Start with the settings and airflow

Check that the thermostat is set to cooling and that the selected temperature is below the room temperature. A fan running by itself can circulate air without cooling it.

Turn the system off before removing its filter, then clean or replace the filter as the manual directs. Keep room vents and return grilles clear of furniture. Carrier’s cooling troubleshooting guide explains these checks for central systems.

For a window or portable unit, use its own filter, vent hose and drainage instructions. Central system advice does not cover every room air conditioner design.

If ice is visible

Stop cooling and follow the manufacturer’s thawing instructions. Ice can restrict airflow further, and melting it does not establish why it formed. Do not chip it off.

LG’s room air conditioner guidance describes restricted airflow and low outdoor temperatures as possible contributors. Use the operating limits for your model.

Arrange the right service

If cooling does not recover, ice returns or a breaker trips repeatedly, contact an HVAC contractor or the manufacturer’s service provider. Include the system model, thermostat setting, filter condition and where ice appeared. These observations help with diagnosis but do not establish that the system needs refrigerant.

For a separate refrigerator, laundry or cooking appliance problem, see our household appliance repair services.