FTX noise

[Wael88]

Hey everyone and happy new year
My ventilation system from Systemair VTR 150 is suddenly making noise. This happened after I got back from Christmas with family. It is not very loud but the noise is noticeable.
Now Im in the middle of selling the house and I feel responsible to fix it. Im quite handy and I fix a lot of things but not such systems. Has anyone experienced such a thing with a heat recovery ventilation system or FTX?any clue of what possibly could have happened?
Thanks in advance

 

[huggan]

It could be a bearing that gone bad, is it an old installation?

 

[Wael88]

It could be a bearing that gone bad, is it an old installation?

Its three years old.
Which motor’s bearing breaks down first?