Volvo: air conditioning compressor does not come on, air conditioning compressor, side pipe

Question
where are the power and compressor and sensor wires at on the compressor.how do I tell the different

Answer
Jim,
Just look at the compressor you will see the power wire some are green, and some need a ground that is black.
Some models have a drier in the system that have a pressure sensor on it and has wires running to it.  Other models have a sensor in the high side pipe also has wires to it, and a sensor in the low pressure line also with wires. The wires that come out of the wire harness are power wires and the wire that will go to the block are grounds. Some models that have a sensor in the low side pipe or on the drier are wires that if the pressures are ok allow current to pass through and complete the circuit.