Error H2 - fan goes onto high power cold mode

Fan is on medium heat for about 20 mins, and then shows H2 error code flashing, then blows cold air at full temp. I'm guessing it's an overheating error. Also, the hot air only blows out one side of the tower, cold air out the other side.

There was a lot of dust around the base of the tower in all the little holes which I vacuumed out, but the problem persists.

Guessing one of the fan heaters has burnt out? About to try taking it apart, but wanting some guidance first!