Purchased a 2012 R350 early last year and have been thoroughly enjoying it. First time Mercedes owner so the knowledge base on these forums have been very helpful.

Purchase was back in the Spring of 2023 so we didn’t have to use heat until things turned cold by us (NY). Now I notice HVAC is not distributing heat evenly throughout the cabin. In either auto or manual modes heat only comes out of the front floor vents. I understand that getting heat out of the center dash and rear vents is not an option by design but the rear floor vents and windshield defroster only blow cold air regardless of temp setting on climate control.

After researching the forums I tried resetting the climate control using the defroster/recirculate buttons but this did not activate the reset mode. Is this the correct procedure for a 2012 model?

Wondering if diagnosing this requires STAR or if an independent mechanic can use a non-MB code reader. Seeking tips on the best way to resolve this issue.

Many thanks.

Okay, you are going in the right direction... HVAC module needs to be scanned for faults.

You can purchase a "LAUNCH cReader Elite Benz" scanner for about $150 - It will empower you to really work on your car modules.

HVAC Module ("AAC") has many ways to require service: actuators and valves get disfunctional. You need to know what your car is up to in relation to its 40+ modules....

Thanks for your guidance, will give this a shot.

I am also looking into getting set up with Xentry which even with the learning curve seems like a worthwhile investment.