An air conditioner should never be switched off and right back on — that can trip its safety and even damage the compressor. If you cut power to it, wait at least 5 minutes before turning it back on.
Set it to COOL and drop the target 3–5 degrees below the room temperature. Set the fan to AUTO. Replace the batteries if the screen is blank.
A dirty filter chokes airflow and is the number-one cause of weak or warm cooling — it can even freeze the system. Replace it if it's dirty and give the unit time to recover.
If you see frost or ice on the indoor coil or the copper lines, the system has frozen up. Turn the thermostat to OFF and the fan to ON for a few hours to thaw it, then try cooling again with a clean filter.
Central AC often has two breakers (indoor air handler and outdoor unit). Push each fully OFF, then ON. Also check for an outdoor shutoff box near the outside unit.
Make sure the outside condenser isn't buried in grass clippings, leaves, or debris, and that the fan on top is spinning when it runs. Gently clear anything blocking airflow.
You smell burning, see sparking, or the outdoor unit is buzzing loudly without the fan spinning — shut it off at the breaker and call us rather than forcing it.
Cool again — good. If it can't keep up on hot days or freezes up again, send a work order so we can check the charge and coils.
Tell us whether the indoor fan runs, whether the outdoor unit spins, and if you saw any ice — that points us straight to the cause.