The refrigerant cools by expanding the gas through the evaporator coils. Low pressure on refrigerant makes it is expand more than intended. The greater expansion causes a greater temperature drop, thus it freezes quicker. It is a little counterinutitive.

Also, leaks in the evaoprator can cause a freeze around the leak due to the rapidly expanding gass when it escapes.

Also, issues with airflow through the evaporator can lead to freezes. That is usually due to a clogged filter or problem with the fan motor.

 

Thanks, guys, for your reply.

Just an update: today Lexus dealer told me that the issue is a known issue (multiple people reported). They are waiting for Lexus manufacturer for a fix and will let me know.

I have a bit doubt on that and am thinking to going to different dealer. But on the other hand, I did see from record that the previous owner did report the same issue as early as 2018. So, I don't think there is a leak since it would not be working after 3 years. .