A/C fan, heat and defroster not working

About a year ago I had to replace my blower motor resistor. Then after about a year it turned bad again and replaced it but was having it intermittently work again. Proceeded to replace the blower motor but didn't work. I sent the motor that I just bought back as it wasn't a clip style like the resistor took. Replace the resistor again and started working for a short while. Now it's doing it again and bought new resistor/blower motor and not getting anything only when I bang on dash. Maybe it's the fuses? I've plugged and unplugged the ones that connect to the A/C, fan checked the see through ones. What might it be? Any help would be appreciated. I have been trying to fix now for a while. I don't mind not having the A/C or heat just have to have defrost before winter comes.