I have a 2010 S550 with four-zone / rear-seat climate control. The vents for the left-rear passenger are all blowing/venting HOT air. I've tried moving the temperature setting from LO to HI, HI to LO, powering off and on, and tried changing settings from the rear control panel and the front COMAND controller. No change. Pretty much stuck on hot (max hot) for the left-rear seat zone. It's a temperature issue for this seat, the controls from either the rear seat controller or the main COMAND controller function to change where the air is vented to, and the temperature changes work fine for the right-rear passenger from either controller. On any other car I'd assume its a stuck blend door or actuator motor, but with the complexity of these models, I wanted to rule-out a computer calibration issue if that is something to consider? Also, I understand that on some other models there is a way to access error codes from the climate control system. Is that possible on the W221 and if so can you provide that procedure?
You really need help from a dealer tech if you cant read it in your own question, i would point out that dealer test equipment is most reliable, and use of service bulletins to find whats the latest fix for this kind of issue on this make and model. you are asking to research and find what he fixes daily. please consult them to get answer if you can.. if they are not available where you are there is always benz world and pelican. some technicians frequent those sites and answer what they can.
SOURCE: 2004 suburban rear a/c only blows hot air
ase mechanic:
there are separate actuators for the blend doors. one for heat and one for cool. they work opposite and in conjuction with each other, if that makes any sense. ones open, ones close, for each different climate. sounds like the the cold one isn't opening in the rear.
SOURCE: Air conditioner blows hot air after 30 seconds on
I have had this problem. I am not a mechanic...so to correct the issue temporarily, I simply turn off the car and restart. This has worked everytime for me. In extreme cases, I think you can also remove the AC fuse and start the car, which will also reset the computer. I also think that by taking the climate control off the "AUTO" setting has worked in the past.
SOURCE: I can not get hot air to come through the vents on
you need to check under dash to make sure plastic heat pipe is in place to that vent
SOURCE: I am working on a 2003 Chevy trailblazer, and the
Bob,if this is an automatic(climate control)type system,it could be a computer problem or electronic board problem.
I really wouldn't know where to start,except by phoning GM service manager and lay the problem before him.He may know EXACTLY what it is and tell you right over the phone.Sorry I'm no help here.(:^( don-ohio
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