My Kitchenaid refrigerator stop freezing. It still gets cold on both sides. But the freezer does not freeze anymore. I was told that it was the coils need cleaning, so I blew them ouy with my air compressor and I also cleaned the drain tray. It still does not freeze. What else could it be?

It could be a freon leak, or the compressor is not staying on.  If you can hear a clicking sound coming from the back every couple of minutes, your compressor overload is kicking off.  More than likely you either have a freon leak, or a defective compressor. Check the warranty on your machine as many manufactures warranty the sealed system for much longer than the rest of the refrigerator.

this is Thermador refrigerator, but this is exact copy of built in Kitchenaid, Here I found leak at Evaporator. Defrost heater got deformed and it burned out couple holes in evaporator coils. I replaced evaporator and heater and charged it back up with r134a freon. Hope Thats Helps.