[Optherion]

Car was in the shop again for a week. Got it back and been testing for a bit. A lot of parts were replaced, recharged and put back. The air is a definitely colder. I took temperature measurements around the vehicle and it is in the acceptable levels of blowing "cold" air at the vents. However with the thermostat set to 60 MAX, after a hour it drops the interior from 104 to 85. Mildly comfortable. No one is going to get in this thing in and complain its cold.

I worked with my service adviser and the best way we were able to get the coldest air was by disabling the "rear AC control" setting in the iDrive vehicle settings entirely. The AC blower kicks on to a high speed and the air is actually 2-3 degrees colder at the front driver/ passenger vents. (No air flow to the back) Anyone can use a temp probe and verify this.

Also to note for other users:
After driving for 45 minutes I temperature logged my AC vents at 59 Degree air temp. I let the car idle in the driveway for about 20 minutes, and then took a temp reading again, with exactly the same AC temps. System is stable when idling regardless of vehicle speed.

I also did a cold start the following day. Outside temp 104. Let the car idle for 15 minutes in the driveway and air temp was 60 at the vent without ever moving the car.

Currently in testing with multiple temperature sensors. I shouldn't have to go through all this scientific effort after 15 years of BMW ownership and living in this same climate. I am still on the fence that my X5 has the worst AC of any car I have ever owned. Im starting to wonder if theres enough air flow for the cabin size or why it cant entirely cool down the car.

To throw the biggest wrench in the entire loop. My rental 2017 430i would freeze my butt off. Much smaller cabin space obviously. Sigh. Tomorrow I'm going to drive a friends Black on Black Dodge Durango which has the in roof rear air. It puts my X5 to shame with the AC cooling. I am also going to use another 2017 x35i for side by side testing. Stay tuned.

If anyone else lives in a climate with 100+ Degree daily temperatures and AC issues please chime in.