03 oddyssey crackling sound from dash area

I noticed a crackling sound coming from the blower motor area. This crackling sound occurs even when my fan/ac is turned off. I'm guessing it's the resistor that's making the noise (common failing problem). However my fan speeds are all normal, the fan has never failed, but sometimes I noticed my AC does not turn on. It says "AC ON" on my climate control but it blows hot air out of the vents, like if the heater function was selected. When this occured, I lightly banged the blower motor area with my palm and my AC was working again. This all seems very strange and I know there's a bad part in there. I just don't know which part I should be replacing. Any ideas?? thanks