Got one last week and finally got around to giving it a test run today. I read in the instructions that the fan is dual speed i.e. runs slowly while it is cool and speeds up when it gets hot.

I've had the amp running all day today and the fan hasn't come on at all. Is this normal? Does it cut in at a certain temperature? Couldn't hammer it too much because of the neighbours

Thought I would check before I use it for a function.

I've got a 3 and 4. The fans come on slow (at start up ) and are on all the time. Never had them running full speed or hot really - even 4 ohm bass bin use (sorry, sub as they are called thesedays LOL)

There was something wrong with it. Phoned the shop and they said bring it in and someone will look at it but not today. Explained I wanted to use it this afternoon so they offered to hire me one.

I said no in slightly stronger terms so they swapped it for another one which seems to work fine.

Well done for spotting that.
Much better than using it for a gig and it fries itself and possibly the speakers too !