Three days ago unit was icing over and had it serviced. It took 3 lbs of freon. Unit worked fine for three day, and now the ac will come on with the thermostat, but in about ten minutes, the air starts blowing warm. Fans are still blowing and outside unit is still operating, but air out of the vents starts blowing warm. The temp. at the vents at first is about 65 degrees, but again, in about ten minutes it starts blowing warm. Nothing is icing over and everything is clean. (Filters, a coil, etc.) If I turn the fan on and shut off the ac for a while, and then turn on the ac, the same thing happens. Starts great, and then the air warms up.
What is going on??

Thank you for your help

Richard

The unit may have a leak that hasn't been found... sometimes a service valve will start leaking after being disturbed. Look for an oil stain on the tubing, coils, and so on... Be sure the service valves are capped... run the unit, then check for leaks with soapy water, looking for bubbles... Good luck...

Its hard to say but the system may be over charged and over heating the compressor. If you have a dirty evap coil or lack of air flow it will make it look under charge with refrigerant and in turn the service tech may have added refrigerant when it was not needed,