Performed a full system home care on single home. System is from 2002, on the furnace. We found a large amount of rust inside the unit, filter, extremely dirty, blower wheel, dirty, no wet switch. On the outdoor unit we found the capacitor completely failed and hard start kit needing to be replaced. Also found 19 PPM of carbon monoxide leaking into the home told customer to run heat at their discretion. Based on our findings today, it might be time to think about getting a brand new system.