I arrived for a recall on a blue club member. I inspected the system and found the system to be running at 4 deg subcooling which is where the subcooling was set at by us two services ago. I inspected the system and found that it calls for 12 deg subcooling per manufacture specifications on the systems data plate. I made the homeowner aware of this and I did not charge to a diagnostic fee to add more refrigerant to the system that we/I missed on previous services. We agreed to add what refrigerant was needed to get the system running. I added three pounds of R410A and set the systems subcooling to 16 degrees. And the range aloud is + / - 3 deg from 12 = 9 - 15. Once the systems subcooling was running properly I found the temperature difference across the evaporator coil to be 4.3 deg with a subcooling of 16. I let the system run for 30 minutes with correct subcooling levels per a TXV set up and the systems temperature difference from supply to return only gained 2 deg to 6.3 deg. And s