York condenser unit not kicking on via thermostat, but works fine with override.

Problem:

York E1RA036S06D (air heat/ac pump) condenser unit fails to turn on via thermostat controls. Operates only when using the override button on the contactor block.
Note: Air is handler working fine.

Testing:

• Air handler works fine but will not shut off as temp never drops (seems normal, right?)
• Condenser capacitor has been ruled out since contactor button engages system and effectively cools, but stops the moment the button is released.
• Voltage at base of contactor is 240 as should be expected.
• Tested voltage from contactor on the sides (low voltage) and got nothing. This may be the red flag, but I'm not certain.
• No noises or strange behavior from the unit is detected when using the manual button.
• Nothing seems to be shorted in the control area (no dead lizards, ants, etc.)
• No char marks or obvious signs of an electrical short can be seen.

Conclusion:

I was told on another forum that my initial thoughts were incorrect. (They would not elaborate due to legal concerns) I assumed that the problem must be related to either the PCB or the contacter. After being told that I was likely incorrect, I checked the low voltage contacts on the contacter and found that they were not energized. This makes me think that the problem exists in the wire or the thermostat. I replaced the wire from the air handler to the condenser and no joy. So I'm left with either the thermostat or the wire going from the thermostat to the condenser. If anyone has any other thoughts, I would love to check them prior to calling a pro.