The most common sign of central air conditioning and heating problems is the thermostat. Adjusting the thermostat to a different fan setting or temperature may solve many problems associated with central air conditioning.
Check the temperature of the air coming from the central heating ducts with a meat thermometer. If the air coming from the ducts is hot rather than cold during the summer, determine if the thermostat is set to Fan or Auto. If the thermostat is set to Auto, it could need replacing. Make note of significant discrepancies in one room as compared to another.
Adjust the temperature to a lower setting on the thermostat. If the air in your home doesn't cool, recheck the temperature of the air coming from the ducts with the meat thermometer.
Evaluate the outside unit of the central air conditioning. If there is air coming from the air ducts in your home even though the outside unit is not currently running, you may have a problem with the thermostat. Try the reset instructions for the thermostat which you currently have installed.
Check the fan setting on the thermostat. If air is coming from the ducts when the fan is set to the On position, turn the fan to the Auto position. If there is air coming from the ducts when the fan is set to Auto, with the outside unit not running, there may be a problem with the thermostat. The problem may also be with a relay switch between the thermostat and the air handler.
Have your heating and air conditioning system serviced regularly to diagnose, repair and prevent problems that could potentially lead to costly repairs in the future.