2004 c270 heating issue (no heat into the cab )

firstly I hope I am posting this in the right place, it is my first ever try on a forum although I have read 100s of posts.
I am having an issue with my 2004 c270 , im getting no heat at all into the cab ( driver or passenger)
it is a fairly recent issue although I was having the dreaded clicking noise behind the dash, but I did always get heat, now I don't know if its connected but recently had a leaking high pressure pump which I have replaced this week only after which I discovered zero heat in the cab , so today I took the whole dash apart and found the faulty stepper motor. the issue is it has nothing to do with the heat, I now have no clicking but no heat
I don't loose any coolant and coolant is at correct level
car heats up to temp just fine and stays there
im at a loss as to how it can just stop . any advice would be highly appreciated chaps
5

 

Most likely the duo valve under master cylinder.

 

I don't think C Class has duo valve - it's just air blending?


Mine doesn't go fully cold on the drivers side - someone with same issue found it was the controller.

 

I was under the impression mine doesn't have a duo valve ? I could be wrong

 

No duo valve, it’s controlled by flap. Do you have one hot/cold dial or two?

 

I have 2 . one for drivers side and one for passenger , both don't change the heat in the car , although when I turn them I can hear a change in the air being blown , so would seem they are doing something but the heat doesn't change

 

same as this one

 

I would locate the two hoses where they pass through the bulkhead under the bonnet. See if both feel hot.

 

I could only find one entering into the bulk head , same as the image above

 

Correct my miss reading your post.

 

I was also having trouble with my heating. Kept air locking. This is how I have solved it after trying various methods. (two weeks ago and still working)
Drain the antifreeze into a bucket.
Disconnect the pipe next to the expansion tank. One of the pipes head towards the bulkhead the other the radiator.
Stick a garden hose in the pipe that head to the bulkhead and flush. Remember to close the drain plug and keep the expansion cap on.
After a good flush pull the hose out and quickly connect the two hoses again.
Top up the expansion tank with water. then get the engine up to temperature. I now was getting heat out of the heater.
I have a clean Pella pump and set it up with a three-way hose connector. Wound Gaffa tape on the garden hose so it made a snug fit in the expansion tank lid. see photo. I then sucked out as much as possible with the pump. Then I switched my two taps to suck in my antifreeze back into the radiator. You might need to top up with concentrated antifreeze. Now in no way I am saying this will work for you. But so far it's working for me.

 

yeah could for sure be worth a try, a flush would be the next step if nothing else pops up , jjust baffled how its happened so quickly literally over night

 

You mentioned it happened after changing the high pressure pump - there's nothing connected / relating that could cause this, is there?

 

this is what I was wondering although I don't see how , its the only thing ive done or changed recently, I was kind of hoping someone would say yes theres a wire or sensor right near it that ive disconnected or knocked ha

 

so just discovered my water pump pully had snapped in half so unsure as to if that's affected it at all, the belt was seated still but new one ordered will update if its had any effect at all

 

Can't tell from your description but I guess if that means the water pump wasn't working there's a good chance hat water wouldn't be getting into the heater matrix.

Did you run the car any distance like this? I know these engines take a lot of warming up but I'd have thought it would overheat fairly quickly if the pump wasn't working.

 

yeah I have reason to believe its fairly recent , and it was seated on the pulley quite well and spinning it , so im doubtful this is the fix but I cant test anything until ive fixed it