Front drivers side speaker not working
 

In the last 6 months I have removed the stock sat nav unit and in its place installed a car PC. Not long after this, the drivers side front speaker suddenly stopped working. I've put up with this until now but really want to do something about it.

I've checked the wiring to the back of the head unit which isn't damaged and is connected securely. The problem affects all the inputs (i.e radio, CD and aux).

The only thing that I think it could be is the fact that I've removed the stock nav unit, I know the voice for this used to come through one of the front speakers, so I'm wondering if this wiring has something to do with it and maybe I need to connect something to the nav wring that's now been disconnected.

The only thing I haven't checked is the speaker itself and the wiring but I cannot see how this could've failed or how the wiring could've been damaged.

I really hope the problem is not with the head unit but how would I check that
anyway?

Thanks for your advice.

Alpine.

Took the door card off today and checked all the connections which as I suspected were ok. I did notice something strange; when I fade the head unit to the front right (the affected speaker) I get nothing, however when I fade the left back in or rear back in, I do get some sound, however only from the woofer and not at the same level of the other speakers.

From the tweater, all I can hear is static, again at a lower level to all the other speakers.

I checked all the connections to the back of the head unti which are present and correct.

I just can't work out what the problem is, it's very frustrating!