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No heat inside the car...

8K views 29 replies 4 participants last post by  BENZIN 
#1 ·
After some months without driving the car I noticed that the air blowed is not heating, so is it possible to get some hints to find out the cause please?
I read a post here about the replacement of the "heating valve" which is not easy to access but is a good candidate...
How to be sure it's the problem, what should I check before to replace it?
Thanks
 
#2 ·
Yes it is normally the heater change over motor, some have some luck by giving it a whack with something, and have had success doing this once a year, but if really bad then it must be replaced.

Its cheap to buy, but not easy fitting it.
 
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#5 · (Edited)
Benzin, you have a star didn't you? There may be fault code stored (not always!) or then you can control valve directly when warm air should come. Valve is relatively cheap and changing is not as bad as told. Just remove wiper mechanism and you get lotsa more space, plus prepare hook wires which you can use opening the locking clips (practice first with you new valve too).

Edit: if you have webasto, be sure you get right part, then there is extra tube in your valve where heater hose is connected.
 
#6 · (Edited)
Indeed, I was wondering if the motor is blocked -> current surge with probably an electronic fuse somewhere on the control box
or a loose contact (brush) which might both be detected easily according to the control electronics thru Star (have to see what Star can see though).
If it's a loose contact a whack might help as told before. But I have to get a new valve in case it's blocked.
There's no fault info for electronics if a gear is broken since the motor runs and no surge detected...

I'll check what are the options Star gives me tomorrow; I took the car this morning and no heat, last time I drove the car was some months ago but at the time the weather was nice.

Thanks mersum1es, I'll remove the wiper as you say, probably just some bolts like on my W124.

I got a Webasto, I need a special part... and it looks like it's 2118320684, confirmation would be great !
 
#8 ·
This is a very common problem, it also applies to the 230 and 221,216 they are cheap Mickey mouse motors costing just £32 in the UK.

My 230 has not been used for 2 months and that one has failed.
 
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#10 ·
I replaced the valve today, curiously the old one was in open state???
So I checked the water circuit and noticed that there's also a small electric pump near the SBC pump, probably the return line of the inside heater, verified that it was not blocked and running.
Everything was fine and still no heat when the engine was at 85°C !? (not driving)

After that I drove the car and about one km or so the heat came back without notice, can't really understand what happened but it's my experience.

Thanks again for your help and good advices, I hope it will stay hot during the cold...
 
#12 ·
Aux circulation pump is for webasto heater, yes can be used rest function too.

Are you sure your heat was coming really from water, not electrical heater? I remember reading a case where heater rad was blocked. Cure was flush the heater rad ( upper and connections).

If no avail, you front SAM controller chip may be gone bad (rare but possible). Instead of changing whole SAM chip can be replaced
sorry about language, again :)
Mersuforum.net ? katso viestiketjua - W211 etu-sami vaihto / korjaus
 
#13 ·
I can't know how to verify the origin of the heat today: it happened when the engine was hot and running, last week in the same condition
no heat at all ?! (when engine was cold or warm)
Is it the electric heat when the water's engine isn't hot enough for example ?
How can I check if the heat comes from the engine or from a resistance ?

p.-s. can't see the video right now, because of some internet problems I don't have the good amount of bandwidth.
 
#15 ·
Ok, I see, I'll do that tomorow, thanks again for your very specific help and nice vid.

This driver is for the motor of the valve I'll check with Star so I'll know if this driver has a problem.

But still can get how to know if the control motor valve is working with Star, there's no feedback system with this little valve ?
 
#16 ·
Connected Star, didn't see any info in the menu to control the valve or the electric heating system either(don't even know if it's present on my car with automatic Klima), there's all possibilities to control actuators for air flappy: left and right, up an down, to control the air turbine, and to see the value of theses parameters in real time (temp, pressure, amp,...)

Maybe in the specific menu that I didn't find out there's a control for the valve, but as there's no feedback to the little motor I don't know how the system may know if it's working fine!?
 
#17 ·
There is a control test for valve, I have done the test myself... cannot recall where it was found. Plus you could see current (Amps) fed to the electrical heater pack (it's divided), and you could also control Amps yourself.

I think there is no other feedback from the valve itself than system checks either resistance or current of control signal. Test itself was based on check if heat came in cabin when valve was commanded open. Likewise electrical heater test you could feel difference in heat when more power was fed. That's why there is often no fault code even valve motor is faulty. And then sometimes it may burn that chip (actually not sure if it can do that, chip should be protected against such things).

One 'easy' DIY check could be that you touch incoming/outcoming hoses of heater rad (water valve). Both should be cold when valve shut (well inlet may warm a bit), and outlet hose should get warm when valve opened.

If I have time I could check later star simulation mode where valve and heater test are found...
 
#18 · (Edited)
Indeed, it makes sense, unfortunately I didn't find it, my car is outside and can't stay a lot now that it is cold...
I checked the returning line to determine if it was electric or water heating and it was hot, so nothing blocked there.
I only use Star a few, I saw the features said previously in the Klima menu.
Btw, did you also check the electric heating systems with Star ?
Thanks
 
#19 ·
I checked the returning line to determine if it was electric or water heating and it was hot, so nothing blocked there.

Btw, did you also check the electric heating systems with Star ?
Thanks
Good thing that water runs like it should. Your system may be fully ok, we are just messing things up...

Yes I did check electric heater because my system is giving fault code. Evidently I have one of the six heating unit open circuit since system shows full current tried to put there (cannot be, 200A, if I recall right, would drain my battery really fast).
 
#20 ·
Ok, maybe that I don't have this electric heating in my car?
200A in 12V gives 2400W... probably not possible for one element: short-circuit.

Is there a fuse for the electric heating in your car? Can't see any fuse related to electric heating in my fuse list.

So the electric heater should only occurs when the engine is running and the alternator is a 180A(2160W) if I'm right.
This system should work a few minutes when the engine is running and cold, was it the case for you? In my case it's cold air in these condition.
 
#21 ·
LOL just realized you have 500 engine...? Electric heater is installed only in diesel cars...

Current sawn in tester is 'asked' current, not real one and I assume because system see no current going (or it see infinite resistance) it tries put full current through... heater IS very powerful, I think 2kW is about right.
 
#26 ·
I don't think that there's a problem on the SAM other that knowing that something doesn't work as it should, I opened the valve and the motor was OK and the mechanism as well, I rather think that there's a cutt-off circuit (motor brushs) and each time the system doesn't open or close when it should there's some abnomalies between temperature of the engine and the heating unit and it goes in a kind of safe mode, it's not an overheating of the chip, there's no reason to think that here. And a little shock on the valve should "repair" it for some time as you told me. When it's blocked it's another story...

The only thing that I can't get is why the valve was open when I removed it !? :confused:
 
#28 · (Edited)
I removed the pump and saw that this little pump wasn't blocked, it's a turbine kind, a false contact shouldn't be a problem other that for the Webasto, I may make a test tomorow by removing the power from this pump before running the engine and see what's happening then , and the pump from the engine really pushed the water to the heating unit (also checked that).
 
#29 ·
Really odd your fault, yes the pump is the same as used over the whole range for year, and the water should pass through it, it it be a blockage in the heater matrix, as there is nothing more to it. The engine does need to be at 90c to get the best from the heater, when the thermostat has failed and engine only getting to 60c the car will feel cold as its blown air.
 
#30 · (Edited)
Indeed, I ran the car without the pump's power today and the heating worked, didn't notice any difference, the air came warmer and warmer with the rise of the engine's temp.

I had a bad thermostat on my W124 last year and I had nearly cold air inside the car but the engine's temp was low (60°C).

So a blockage in the heater matrix is the best candidate with maybe an intermittent problem with the valve.

Thank you for your help.
 
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