I have a 96 deville w/89k mi. The problem I have is the black plastic housing for the fan motor,condensor? for the hvac is crumbling apart. It is the plastic box that sits next to the firewall on the passenger side. I remember seeing a square scored section on top that reads cut here for service. About 1/3 of the plastic has chipped away and I have temporarily patched it with duct tape.Is there a replacement part available? Also, does it hurt to be exposed? I am not sure if these parts need to be airtight.I'm not even sure what this box contains;just guessing. Any help is much appreciated.