Also, I think some of you are really going overkill on drying the inside of your units.
Do you ever do a dive, get out for a surface interval, then do another dive starting with a not-bone dry unit? Okay, then why do you ever need to accelerate the drying process? If you are diving tomorrow, why does it need to be any dryer than it would be from just drying it out using the shammies and leaving it open overnight?
I almost never open my unit between dives on the same day. Much less do anything special to dry it out between dives. The exception would be if I heard any gurgling in the loop at all during a dive. In that case, I would open it up, wring out the shammies and use them to wipe out the interior (repeat as necessary), then wring out the shammies a final time, put them back in, and go for my next dive (after appropriate surface interval, of course).
I do have 2 sets of shammies, so sometimes I will use them on alternating days, to start each day with bone dry shammies. But, really, if I just dry my unit out with the shammies, then leave it open and the shammies out to dry, I would have no problem putting it all back together and diving again almost immediately. For sure, the next morning.
What am I missing? What do you think the effects might be if you left your unit open, to air dry, that you are preventing by using a fan to accelerate the drying?
If your environment for drying your unit is humid and it just won't get dry on its own, I can see using a fan dryer to get it bone dry before storing it. But still not bothering with that overnight before a repetitive dive day.