My son started coughing and believes it’s the ducts when the evaporative cooler was switched on in mid Dec 2016 for a few days. He went away for 2 weeks and just came back and started coughing again but we haven’t used it for the time he was away. Is some kind of testing available? I have an evaporative cooler with 5 duct points upstairs and a central heater with 11 duct points on 2 floors. How much to clean the ducts and the units? How long does it typically take to clean a house such as mine?