My S500 hot air with A/C on, works with the blue button press and side vent only
 

Hello guys, thanks in advance for the help. My S500 is blowing hot air with the AC on. The AC blows 40 degree air in the center 2 vent only if I press the blue button between the 2 center vents. The side vent blows hot air no matter what I do, so I just shut them off.

Is this due to a bad duovalve?

Any help?

check your refrigerant charge...

Refrigerant charge is as good as it can be. I was in the AC shop after I repaired my AC. With the AC just charged, still hot air on the side vents. I mean not just hot air from outside, really hot!! The hot air blown is at 90+ when outside temperature is 70.

Is the compressor turning on?? have you checked the ccu for error codes??

The CCU is not giving any error code. If I do not press the blue button in the center vent, all the vents will blow hot. However, if I press the blue button, the center vents blow 40 degrees.

You may need to have the car scanned then. it sounds like an electrical, rather than a mechanical issue. CCU could be the problem. If it is, you can send it to programa and get them to rebuild it for a reasonable cast.
I'm sorry to say that the electrical issue is beyond my ability to help with. See if you can get M.B.Doc's attention....