Performed preventative maintenance on the system. Cleaned drain, checked coils, tested/inspected all electrical components, checked refrigerant pressures, and tested operation of the system as a whole in both heating and cooling modes. I did recommend adding a UV light or air purification system and the customer agreed it was a good idea so 8 8 stalled a 24v UV light while here. The customer also had a customer supplied thermostat he wanted installed so I installed that for him and tested its operation. This unit is currently operating correctly, maintenance is now complete.