The reason the heater control sparks when you remove it is because the assembly is the ground so that's normal. Here's a quick link to the schematic: Heater Diagram Looking at the schematic it should have power with the ignition key is in the on or ACC position. If it's getting power with the key in the Off position then maybe your problem lies with the ignition switch, which maybe also the problem your having with the turn signals. Now I looked at the turn signal schematic but it's useless. So somebody with a 67 will need to chime in if the signals still sould work with the key removed. If so then they're good. If you know for certain that this isn't right or it just recently started happening have you done any work under the dash etc that may have caused this? Sometimes we inadvertantly create problems while fixing others. Hope this helps.