Cleaning is generally safe for older aircon units and is in fact more important for aging units than newer ones, as older systems are more prone to mold buildup, clogged drainage, and reduced efficiency due to years of accumulated dirt. However, technicians servicing older units should exercise extra care during disassembly and reassembly, as plastic components, rubber seals, and drainage trays can become brittle with age and may crack or break if handled roughly. A chemical overhaul on a very old unit should ideally be performed by an experienced technician who can assess the overall condition of the unit during the process and advise the owner on whether continued servicing is still cost-effective or whether replacement would be the more practical long-term decision.