Here are three of the most common issues and what to do.
Air won’t come on: first check outdoors to see if the condenser is operating. Check that your thermostat is correctly set. Try adjusting your thermostat by 5 to 10 degrees to see if that solves your problem — and make sure your thermostat is set to cool.
Air is blowing out warm: You might have a clogged or soiled air condenser. The first step is to inspect the exterior unit and clear up any trash or weeds that are obstructing air circulation. If there’s no obvious problem with your equipment, have a professional run a diagnostic on it.
Your home is still not cool: You could have a unit that is too small for your home. Remember that your system should be sized to keep your home cool on a typical summer day. The typical system should be able to sustain a temperature differential of 20-25 degrees between the outside and inside temperatures.