I have a 1998 Honda Civic. My heater fan was only working on full speed. I found that the blower resistor was burned out (open circuit). Replaced the resistor and everything was fine for one day! Now I have the same symptoms (and probably burned out resistor). Fan still runs fine at top speed.
Fan must be drawing too much current? Anyone have suggestions re fix? (Do I need to replace the fan, even though it works fine at top speed)?

Have you tried to turn it by hand to see if it is tight ??

Good idea to rotate by hand. But do I need to remove the fan to do that?

Not sure on the 6th gens, If you have a cabin filter try to access from there. You could also measure the current draw for the fan (not sure of specs though)

Have you found one of the free factory service manuals for your Civic on the web ??

Very helpful and free.

the blower motor has mechanical resistance therefore causes to draw high amperage which the resistor only draw a certain amount. i suggest changing the motor or if u know how to rebuild the armatures, windings all sorts of stuff.