I have a 93 civic dx and I recently bought some power door locks and installed them and they have worked perfect for like 3 weeks already, but just yesterday i installed my sub and my power door locks stopped working.anyone know what happen? or how to fix it

 

Does the sub tap into the power lock circuit? Have you checked for a blown fuse?

 

also after i installed the sub my back winder defroster stopped working... i checked the fuse for that and it wasn't broken or anything

 

On the defroster, turn the key on, push the button, and check if voltage is reaching the wires on the back window (should be 12 volts from one side to the other). There is a fuse and a relay in the box under the hood. Even if the fuse under the hood is blown, the light on the button will still light up.

If you have voltage at the window but it doesn't defrost, the printed wires could be damaged.

And if your car is a hatch, the wires feeding the window could have broken where they flex every time the hatch is opened.