Maintenance on hvac system. Furnace is 20 yrs old and ac is 17 yrs old. Replaced weak capacitor(40+5 mfd) on ac unit. Air filter has not been changed since we were here last year for maintenance. Informed customer that system will break down if filter doesn’t get changed more often. Blower wheel has a build up of dirt on it. Quoted blower cleaning and air cleaner for the home. System is running safely for now but with the age of equipment it’s only a matter of time before parts start to fail.