4 yr old GE Profile won't make ice. I replaced the water filter. Water is filling the icemaker but it is not freezing. I have cycled the icemaker by the reset procedure in the service manual. No change. The actual/set temps of the freezer and frig are within 1 degree of each other set at 1 and 39. Interesting observation...when it was working, I had cold air blowing from the upper duct into the ice compartment. Now I don't from the upper duct but I now do from the lower duct which according to the service manual is the return duct to the freezer. I see there is an ice blower fan supposed to blow cold air from the freezer into the upper duct and return by the lower duct so how am I now getting cold air blowing from the lower duct only? The airflow diagram in the service manual doesn't show a fan blowing cold air thru the lower duct. At this point, I don't know if I have an ice fan issue, a control board issue or an icemaker assy issue. According to the diagnostics, all the thermistors passed. Any ideas?