HVAC maintenance helps landlords retain quality tenants and control their ownership costs. For best results, centralized and decentralized heating and cooling systems should be serviced in the spring and fall. Technicians can lubricate moving parts, measure refrigerant levels, clean the coils, and check the belts and bearings. Landlords should also consider supplying new air filters to tenants to prevent unnecessary wear and tear, and unit breakdowns related to restricted airflow.