When I arrived I found that the voltage enhancement system was swollen. I spoke with the client about his different options and he chose the hn13a. I replaced the voltage enhancement system and checked operation. I found that the head pressure was extremely high due to a dirty outdoor heat transfer media coil. I then spoke with the client about my concern of the dirty coil and that the system might be low of refrigerant because of my low delta. We then enhanced the option to a Hn13b. I cleaned the coils and ran the system and found it was 2 pounds low on refrigerant. I did find loose caps and a little oil on the Schrader. After adding the refrigerant I tested the system and found my subcool at 8 degrees with a 17 degree split. The system is now cooling properly. I did highly recommend maintenance but the client declined at this time.