Why does my central air conditioning unit start to blow hot air after it has been blowing cold?
it blows hot air after about an hour of blowing cool and when i turn it off for about 15 minutes then turn back on it blows cool. this continues through the day. There are a number of potential reasons for this to occur, but the symptom is probably the same with all of these reasons. What is likely to be occurring is that the unit starts off seemingly working very well, then after a while the temp. begins to rise. You will usually see a difference in the volume of air coming out of the ducts as well. At this point the evaporator coil is probably icing up either due to a low refrigerant charge or a restriction in the airflow. The restriction can be from a collapsed or crushed duct or a plugged filter or plugged coil. As the icing of the coil continues, you will get less and less performance until the motor starts to create more heat than you are removing. Shutting it off will allow the ice to melt and then you can start the cycle all over again. If the filter is plugged, replace it. If
