Came out to do maintenance on Trane AC. Customer said system wasn’t cooling properly and was freezing up. She already changed the filter in home. I checked the condenser over and found system low on refrigerant. I discussed with customer about what I found. They are moving and just wanted to get it cooling properly. I added .9lbs of R22 to get systems superheat back in range. I then proceeded with checking all the components to ensure system is operating properly. Cleaned condenser coil thoroughly. Evaporator coil is old and in rough shape, so I recommended replacement in the near future.