I have a 2010 Mercedes-Benz S550. So my hater stopped working a few months ago. No biggie its summer. Its one of the actuators. Just to be clear i have no heat anywhere, nor left nor right. Mechanic said is the central one in the middle. Can anyone confirm theres a central one and if so does anyone have any documentation on how to replace? Do i need to remove the whole dashboard or just the top? I know theres a left one and a right one. Any help with this would be appreciated.

 

This may sound a silly suggestion but check that you have enough coolant in the engine. Level in the expansion reservoir does not always tell the truth meaning you can have correct level in that reservoir but coolant is low in the engine/radiator.

Loss of all heating is one of the symptoms of low coolant in the system.

 

As far as I can determine, and I hope someone will correct me if I'm wrong, there is no "central", master blend flap in the W221. I've been poking around in this myself, reading through the WIS trying to get a better understanding of the automatic climate control system. There's an upper left blend air flap, lower left, upper right, and lower right; then there's a fresh/recirculated flap, and flaps for left and right defroster and each of the vents. The four blend flaps control the temperature, though, so if one of them fails it seems to me it would affect just one area of the car, not the whole car.

There is, however, a heater water control valve located just in front of the firewall on the driver side. That controls the flow of coolant through the heater core. It's not expensive, but make sure you get a genuine Mercedes part if you only want to do it once. They are a known failure point, and the housing can get brittle with age so it's not a bad idea to replace it anyway. There's also a heater water circulation pump that does just what it sounds like it does. When the heater is ON, the valve opens up and the pump runs. Both of these can be tested with DAS actuations. You can open/close the valve and see if the air temperature changes; with the engine off you can turn the pump on and off and listen for it.

If you do replace either one, be ready to do a vacuum fill of the cooling system, as you'll end up with air in it that will give you fits forever if you don't.

 

I also think it could be the heater water control valve near the firewall. Mine failed (in Winter) and I had no heat at all. Replaced it with a real Mercedes part. Not expensive.

Good luck.

 

100% heater valve. Use genuine Mercedes benz parts.

 

So I already replaced the control valve. I also check coolant already. Coolant comes in and out both way like it should. My next question would be, is there an actuator like a primary one? One that lets the hot air come in then gets distributed in any way the actuators are set to? Something is not letting the heat come into the dashboard and onto the cabin, Would it be the right upper one?

 

You have not mentioned if fault codes were pulled this will identify malfunctioning actuator, etc.

 

 

I will run the obd today to see if anything comes back. I didnt know those threw out errors. Thank you.

 

Depending on your scanner it may not but Xentry or MB diagnostics should.

 

My iCarsoft MB II reads flapper codes. I have the center console driver side flapper intermittently malfunctioning and it gives error. It is not a normal DTC. It reads actuator not working or something like that. It is the flapper that controls air flow thru the vent, not the mixing flapper.

 

do you Happen to have a link to that MBII?

 

If you get a scanner there are better ones at about the same price. dfwdude in 212 forum just got an iCarsoft V3, which I think is a lot more capable scanner. You may want to follow that thread. If I was to buy a scanner I would buy something better than the MB II that I have. Don’t get me wrong. MB II shows lots of things but I think it has some bugs and it does not show all modules in my cars.

 

We recently encountered the the no heat scenario on our 2013 S550. Called a local independent shop, Peachtree City Imports on Friday, Christmas Eve, took the car in Monday morning, and at 3:30pm I got a call saying our car war ready.
It was indeed the heater control valve. Jason, the owner said the replacement is an upgraded Mercedes OEM part.
So for about $550.00 we got our heat fixed and a brake fluid service. I was very pleased.

Many thanks to this forum for diagnostic expertise.

 

that sounds expensive the usual one that reduces heat to the car is 50 dollars and 40 minutes to fit
if you have optional rear AC controls there is an expensive valve in the bottom of one wing (behind the front wheel - drivers side on my RHD car) - this is $460 and a hour to fit, but I have only heard this fail on full heat

 

Did you manage to get this fixed? I am having a similar issue at the moment. I have replaced the heater control valve too. I have also noticed that REST doesn’t like to stay on for longer than 10 seconds and I am not having any issues with the blower.

The weirdest thing is that if I start the car from cold, the heater will work, but if the engine is at any temp other than cold, it won’t work….

I can hear the aux pump running when I turn the heater on.

Code I have from the iCarSoft are ‘heating capacity is too low’ 90A2

 

?

 

Did you solve this problem?

 

Yes mine is solved. The wiring harness under the battery was corroded and worn away. This resulted in some broken wires that controlled the aux water pump. Check this wiring harness cable under the engine bay battery.

 

Did you fix this problem I am having the same issue?

 

Hello,

any shot of sending me pictures of the wires you fixed? I have 2007 and the only battery in front is the starter battery. It would be greatly appreciated

 

Unfortunately, I don't have a picture of them, but when you remove the battery you can see the wiring harness that goes inside the fender. I had a wire cut right through. The wires should be measured before dismantling. In the 2007 car, the battery is also behind the back of the back seat.

 

hello,

how the hell did you get the pump out? I have tried so many different ways but can’t get it out.. i want to replace the harness and the pump.


QUOTE=JarppaFIN;8907575]Unfortunately, I don't have a picture of them, but when you remove the battery you can see the wiring harness that goes inside the fender. I had a wire cut right through. The wires should be measured before dismantling. In the 2007 car, the battery is also behind the back of the back seat.[/QUOTE]

 

I fixed this problem by changing heater control vavle

 

Very typical and common problem on the W221.