Today I had the pleasure of conducting maintenance on an 18 year old Carrier system. Upon arrival, the homeowner stated the system has been working fine. I started by verifying system cleanliness and found the blower assembly and ducts dirty and in need of cleaning. I then verified all amps temps and pressures. I found the system operating within manufacturers specifications. I discussed my findings with the homeowners and recommended blower assembly cleaning and duct cleaning. The homeowners approved of the blower assembly cleaning but would like to take time before cleaning the ducts. I removed the blower assembly, scrubbed, cleaned, and reinstalled. I reverified system operations. All conditions normal at time of departure.