Have a Ruud 10 seer 3 ton split with standard orifice style that has me scratching my head. The suction pressure is low but is stable at about 55-58 psig. The subcooling is right about 20 degF, and I backed the charge down until the suction temp would climb up to about 45 degF. Now the strange part of the matter is the suction temp. It will climb up to 45 degf and will go down to about 30-32 degF and then back up and down. The suction pressure does not fluctuate with this temp change. Head pressure was right at 200psig and it was about 70 degF OA. There is no temp change across the filter drier. The evap coil is clean now, and the airflow across the coil is within the realm of reason. Any ideas????