2010 Mountaineer A/C Compressor will not engage.

[Ruddy]

He thinks the PCM is preventing the compressor from engaging. Anybody have experience with a bad PCM with no codes not allowing the ac compressor to engage?

I had opposite problem. PCM was triggering compressor on/off very quickly rocking the motor and even the body. In a desperation test I poured cool water over the PCM and it would stop the behavior every time.
Since you have a V6 it will be easier to find a replacement PCM. If you want it fixed use this guy:

Keyworks: Mail-in Keys and Ecu Repair services

keyworks.us