Brand new compressor, that isn't engageing anymore. Ive seen post that say that it is the Low Pressure Switch but i do not know what that is. Where is it, and how can I replace it?

 

either you dont have enough pressure for the system to allow the compressor to turn on, or any one of your pressure sensors/switches could be bad. Also if any of the 5V reference signals on the sensors is shorted to ground, the PCM will see low pressure.