I have a similar problem of no heater blower in my Ford Focus, in my case nothing works and when i change the fuse in the engine compartment for the heater fan it just blows , i too had the problem of water getting in through the filter , could the solution bee the same a blown resistor if so are they easy to get to and get out , there are quite a few breakers yards near me so was going to have a go and replace
Regards Dave