Upon arrival the technician spoke with the homeowner about the situation That was going on, the homeowner stated that two companies came out, one company said it was in the coil. The other company said it was in the filter line dryer. The technician that said it was in the filter line dryer, replaced that filter line dryer. So I do not know whether it was originally leaking from there or not. The technician that came out and replace the filter line dryer, also charge the system. The technician checked the charge on the system, the system charge was low. Also the Delta T was only at 10°F. The technician went upstairs to the coil and found that the coil had been previously opened. Technician re-opened up the coil and found that indeed the coil is leaking. The technician does not know whether or not the filter line dryer was originally leaking, but the coil is.