I have a 1979 280ZX 2+2 and need a replacement THERMO SWITCH sensor for the blower/fan on top of the engine. Without the blower going on after driving, the car builds up heat and developes vapor lock or something similar to it. If the blower goes on there's no problem, but most of the time it's not going on, and the blower itself is functional. It's the switch. Nissan part number is 21595-P8100. I've tried dealers and a number of Z-part outfits to no avail. Help!