Since the air con has failed on the Civic (repaired once, failed again after only a couple of months), I rely on the fan especially in the hot weather we are having, but, to be honest, the fan power really is rubbish. I have been wondering whether something is blocked somewhere, because I was sure it has been better in the past.
Then it occurred to me that there must be a pollen/cabin filter somewhere in the car, and since I have never changed it, it may be a bit old. So, a quick net search showed that its easy to check - you unclip the two side of the glove box and fold it down, there is a small clip holding on the front panel of the filter box, and you then have access to the two filters.
Pulling out the first filter showed straight away what the problem was - it was absolutely crammed with crap. It took considerable knocking against a hard surface to dislodge most of the leaves, bugs etc. Getting out the second filter (side by side with the first) means moving it to the side so it comes out of the same slot, and again, it was completely and utterly choked with debris. Again, some time spent knocking out it, and replacing, and all of a sudden the fan blows a gale!!
I have ordered two new filters (£10 from Euro car parts, free delivery), as even though most of the large debris has been cleaned out, it's still fairly clogged with fine particles that are not going anywhere, so hopefully it will get even better!
EDIT : Have now replaced the filters , the picture above shows the old ones, and the fan is now goes up to 11! £10 well spent!