Impeller Replacement Instructions
Using your thumbs, press FIRMLY on the impeller module to remove the entire unit.
Press only the sides of the new impeller when installing to avoid damaging the precision hub bearing.
Insert the impeller so that the half that has the serial number label on it goes in first and faces the back of the unit once in place. Orient one “arm’ straight up (The impeller should look like a peace symbol or an upside-down Y).
My impeller is making a rattling/clicking/whirring noise, is that normal?
It is common for the Kestrel to make a rattling noise with a wind speed from 5 to 10 miles per hour. This is completely normal and accurate.
To better understand why the impeller rattles, one needs to know what is inside. Inside the plastic housing, there are four separate parts. The fan, two sapphire jewel bearings and a metal pin. The fan rotates around the metal pin which is held in the plastic housing by the jewel bearings. For the fan to move freely (to not cause excess friction) there is a small space (on either side) between the end of the metal pin and the jewel bearing. The space between the metal pin and the jewel bearing is what causes the rattle. Some impellers can be louder than others, but the accuracy will be the same.