Performed 1 system cooling diagnostics. Renter stated that sometimes outdoor unit would not come on. Tech inspected outdoor unit and found failing contactor. Tech ran system and checked refrigerant levels. System was low on refrigerant. With customers approval tech added missing refrigerant and replaced contractor. Customer also asked the tech to add leak seal. Customer also agreed to sign up for the eap (maintenance program) for both of his systems. Tech quoted landlord a price and got his approval before any repairs were done. Tech replaced contractor, added leak seal and added missing refrigerant. System was operating at the end of service call. Tech also added new refrigerant schrader caps for unit. Landlord gave tech approval to run the credit card that is on file. Loans lord not available to collect signatures.