Update.. I checked wires & voltage today & the problem ended up being in the thermostat. I didn't try the old one again but the new one was wired right. When I was putting the two halves back together on the wall after checking the wires again it started working. One of the terminal connecti...

Thanks, I'll get my volt meter out & check them this week.

I've searched the forum & found several threads with similar problems but they weren't the same unit as mine. I've got an Intertherm FEH-020HA-04 and the AC (fan & outside unit) won't turn off unless I use the switch on the unit to turn it off. Nothing had been changed & it just started ...