I recently took the heater core out of my 66 mtang
Iwant to mke sure that the switch ,control cables and
all wireing are hooked up and properly working  includeing the blower motor . how do i check this?
and do i need a wireing diagram.?  

If you want to confirm proper hook-up you'll need a wiring diagram. They're available for sale all over the place or you can "google" to see if you can turn up a free one.  

The shortest cable is the defrost. The longest is the air shut off to heater or open trapdoor outside air. The middlesize one is to the blending door, hot air to ambient air mixing. I have diagrams for 65-66, got these free from internet. Good luck.  

http://www.hammar.dyndns.org/wiring/wiring1966.htm

Here you go