Ok guys captured this Image this morning outside ambient 72 degrees A/C unit running approximately 15 minutes before I observed outside condensing unit. Had frost on the dryer and back to where it entered the wall. None on the line in the attic and none on the coil or suction line exterior to the coil. The suction dryer had a 1 LB drop in pressure across the filter. As you can see the coil had no lint build up
Refrigerant low?
Very possible but maybe dryer restriction.
Dryer restriction= Frost will occur at one side of the dryer only.
Charlie observed frost back to the wall.
Just as refrigerant pressure will drop across the dryer, so will the thermal pattern. The dryer restriction will allow a rise in refrigerant pressures on the wall side of the dryer, thus the temp will rise. The compressor is on the frosted side because it is sucking the pressure down past the restriction.
Actually, odds are, you are looking at the wrong side for lint build up. A-frames are usually downstream of the blower/furnace, and air moves from underneath to top. So did you see underneath?
tom
It was a downflow the blower was above the coil