Mercedes W221 S550 (2006-20013) 4-Way Heater Control Valve Coolant Leak Replacement

Easier way to replace the 4-way heater control valve. No need to open the hood to full upright position, no need to remove the wiper blades and no need to remove the window cowl.
Note that the rubber spacer wheel that I referred to is used to make sure the control valve does not rest on adjacent piping that gets hot and may degrade the control valve.

[@sgarsideshaw]

That little round donut spacer on the bottom connection is too keep the unit from contacting the metal lines below the unit. Those lines can get quite hot and vibration over time will probably cause the unit to fail.

[@sinybinl1840]

Do you happen to know what code comes on ?

[@sgarsideshaw]

@@sinybinl1840 I don't think there is a code produced when that unit fails.

[@chadnasir6387]

Awesome video

[@MercedesMechanic]

Keep an eye on all the plastic parts that have coolant going through them because after around 7 years they start to become brittle and break when you touch them.

[@gary8853]

Getting to the two clamps on the driver’s side (heater core hoses) was a B*TCH!! 🤣 thanks for sharing the video tho

[@jasonchoyce1035]

Agreed. Toughest part of the job.

[@doingitdavy1507]

​@@jasonchoyce1035I believe the hose that broke for me, was one of the heater core hoses, I can see it and touch it with hood open, but not experienced enough to know where the other end goes or what part it is. Curious based on my half-ass description if you think it's still a $600 dealership job or can go to a import mechanic?

[@bhasins]

Thanks for sharing. My heater is no longer working either. Do you know if there is a fuse I need to check before I replace the valve?

[@jasonchoyce1035]

Here is a link to the fuse chart and the fuse numbers are 40, 50, 54 and 119 which are on the drivers' side under the front hood. However, 119 also powers the backup camera, so if the backup camera is working, no need to check that one. I have also seen reports that the control valve needs to be 'reset' so it can 'relearn' the algorithm, but I have not been able to confirm that. Hopefully this will work for you, good luck. www.benzworld.org/threads/2010-w221-fuse-chart.2322962/

[@MercedesMechanic]

If your blower comes on and it blows cold when the heater is on, then its the control valve. Its made of plastic and breaks with time.