Your Lexus may be using two sensors, one for monitoring pressures and another for monitoring refrigerant flow. The compressor has a replaceable flow sensor (without removing refrigerant) on the compressor, using a circlip to hold it in place. The error code B1479 relates to this sensor on the compressor. The image with red arrow is most likely the pressure sensor monitoring high side pressures. The pressure sensor protects the compressor from self destruction by sending pressure related signals to the ecm; if pressures are too high or below a specified amount (from service manuals), like a leak or crash resulting in rupturing any ac part that results in releasing refrigerant, this sensor informs the ecm. The ecm disables power to the compressor clutch until repairs are made. There's a trick one video shows of a mechanic using a magnet on an extendable wand to place it above the compressor flow sensor; with engnine idling and ac turned on but compressor not running, the flow sensor was tricked into sending signals to the ecm triggering ac compressor operation. You might be able to do this, however beware of other issues. Loss of refrigerant is a main cause of inoperative ac systems. If incorrect diagnosing occurs, you may be knee deep in ac repairs. Ac repairs are not diy friendly. Refrigeration gauges are needed to assess, indirectly, loss of refrigerant while monitoring operating pressures whether performed with engine at idle or higher rpm (specified in service manuals).
