@nafeesjutt, I assume you are referring to A/C problem code B1423 on your Lexus.
Trouble code B1423 is defined as "Open in Pressure Sensor Circuit/Abnormal Refrigerant Pressure" by Lexus.
Here's a video showing one guy diagnosing and replacing the sensor.
[link|https://www.youtube.com/watch?v=XOOAyq8RQgM|Toyota Lexus Air Condition AC B1423 Open Pressure Sensor Circuit - HOW TO FIX - YouTube]