How to Test Air Vents for Mold

Mold cannot always be detected visually by a service inspector. Although mold can sometimes be seen on an air vent, sometimes it's farther down in the duct. The only sure way to detect mold is to use a test kit and laboratory analysis. This can be done with a professional or through a home test sent in to the lab.

1. Purchase a professional test kit that offers laboratory analysis. These are available online. Simply do a search for it on Google.


2. Remove the dish from the kit carefully. You do not want to touch the inside of it, as this could contaminate the surface.


3. Remove the lid.


4. Pour the medium into the dish.


5. Replace the lid and swirl. Wait for it to harden. This takes about an hour.


6. Find the vent that is the farthest from the HVAC system.


7. Tape the open dish against the vent and close all other vents.


8. Turn the fan of your AC on, letting it hit the surface of the dish for ten minutes.


9. After ten minutes, replace the lid on the dish.


10. Allow to incubate for 48 hours.


11. Recheck to see if any visible mold is growing. If so, send in to the lab for analysis.


12. If mold was not visible, wait another two days. Check carefully. If no mold is visible, you will not need to send it in to the lab. 

All mold is not unhealthy or dangerous. A few strands are. If mold is detected, it's important to see what type it is.