[byootox]

The switch at the bulkhead is the low pressure switch, if you bridge it the compressor it will stay on even if the pressure dropped below safe levels.
Problem with that is it could seize the compressor if there wasn't enough oil being carried around with the gas if a leak developed.
There's also a high pressure switch behind the right headlight area which controls the high pressure side of things it's controlled directly with the engine ecu.
E.g. when the pressure in the system rises it puts the cooling fan on either slow or fast speed depending on the pressure or disengages the compressor for too much pressure.
Also things like a 5-10 second delay before engaging the compressor after start up to allow stabilising of the idle speed.
The A/C system on these cars is of the fixed orifice type rather than having an expansion valve in line to the evaporator which means that the low pressure switch controls the off/on cycling the compressor rather than an ice thermistor on the evaporator with the other type of system.