Just got a new to me 2009 G37 Sedan. Today I noticed that the drivers side vents are blowing cold (AC set to 60 on both sides), but the passenger and rear vents are luke warm.

Turned both to full heat and both blow hot.

Sounds like a blend door or something similar, but not familiar with how these cars are setup for HVAC. Tried looking at the FSM for diagnostics, but did not get too far.

Any suggestions?

 

Look up how to put the AC controller into diagnostic mode, it will cycle through everything and you can verify blend door motor failure with it. I also recommend taking the cabin air filter out so you can get an inspection mirror and flashlight up into the ductwork to inspect it from the inside. Might just he something in the ductwork sticking the blend door. Large dead rats or the positive battery cable cap or something.

 

I tried the diagnostic mode (DIAGNOSIS SYSTEM (UNIFIED METER & A/C AMP.)), but it didn't seem to do anything and make sense...

For the first part, the only action I got was turning the drivers side up, when it hit "41" on display the ac kicked on with fan, then next was "51" with no noticeable action. Every action after that had no noticeable action.