My AC blows out cold air from the passenger side vents but the driver side vents blow out warm air. Is there some kind of valve stuck. I notice also that the AC gets colder when I drive compared to at idle.

take a pic of how the temp thing look like.

You have dual climate control? ie.. d-side set at 78 deg and the P-side set at 65 deg?

Yes I have dual control but they are both set at 60. At times the drivers side will blow out some cool air when I am driving on the highway. I am thinking that maybe it is the belt. I have looked at the belt and it does look like it has cracks in it. It is the original belt at 60,000 miles. I had the AC looked at about a month ago and it was at 68% charge so I put in a can in.

uh oh... you need to change em out.

your AC can be set down to 60F? the lowest i can set mine is 18C, ~64F. WTF?

I don't know how the G35's dual climate system works, but that on just about any other car would be a blend door or vacuum issue.

Blend doors are a huge PITA in most cars.

That's a blend door issue....and sounds like your ac has a leak if you are reading the gauge correctly. Both are unrelated. The bend door that controls the drivers side has failed.

I know on the NSX's, there are two AC fans for separate compressors on each side of the car. If one of these fails, it will blow hot air through the side the fan failed on. It's a really weird experience!

Maybe something similar?

Have you tried putting the AC controller in diagnostic mode to see what function isn't working? On some vehicles you can also remove the cabin air filter and look back up through the ductwork with an inspection mirror or borescope to identify the problem. Just be aware of the moving dampers especially the cabin air one because it's right in front of you with that filter out.

So I came across the same problem and found that my pressures were low, this causes the closer vents to blow colder air than the farther ones. Check your pressure first.