Heater only blows cold air!

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JCBman71

New Member
Joined
Oct 9, 2021
Messages
15
Location
Camberley, Surrey
Car
MercedesE/320CDI
Hi everybody. I am having a big problem with my heater only blowing cold air! I have an early 2003 E/class E320cdi CDI ! After entering the problem on Google, everything pointed to the Heater Duo Valve! I ordered the part with my Vin No. and was assured that the valve was, A 211 832 05 84. After it arrived, it looked like a simple job to replace, as per Google instructions, so I have set about the job!
After stripping out all the facia, and wiper assembly, it looks nothing like the Google photo’s and seems to be located right under the Master Cylinder!
Could somebody please advise if this is the correct part, and as you would need rubber hands to get to the one on my car, whether this is because it is an early 2003 model, and looking very likely that I will have to book it in to a garage, whether this particular location would be easily accessed underneath, using a ramp??
Many Thanks in Anticipation of an informative reply.
Eddie Harrald
 
You are correct in thinking the duo valve is located under the brake master cylinder.
When mine was changed on my W211 E55, my indy removed the throttle pedal assembly to gain access.
Looked a horrible job and not one I'd undertake.
 
You are correct in thinking the duo valve is located under the brake master cylinder.
When mine was changed on my W211 E55, my indy removed the throttle pedal assembly to gain access.
Looked a horrible job and not one I'd undertake.
Many Thanks for your reply Mr. Geed You Tube doesn’t mention this alternative location so unless I get any more helpful advice, I shall have to resort to paying exorbitant MB prices to rectify the fault !
 
Before you go any further, have you tested the valve by powering it directly and proved it faulty? There could be a wiring fault or the controller not putting out power to it or an issue with the temp sensors. The "how too" you saw on line was probably a left hand drive model so no brake gubbings in the way.
 
Many Thanks for your reply Mr. Geed You Tube doesn’t mention this alternative location so unless I get any more helpful advice, I shall have to resort to paying exorbitant MB prices to rectify the fault !
Why take a car of this age to a Mercedes dealer?

You must have a Mercedes Independent close to you?
 
Many Thanks for your reply Mr. Geed You Tube doesn’t mention this alternative location so unless I get any more helpful advice, I shall have to resort to paying exorbitant MB prices to rectify the fault !
As said above, LHD and RHD locations are different.

There is benefit having car tested by SDS...
 
Please excuse my ignorance, but what is SDS ?
I am aware that there are variations on Left, and Right hand drive, but the Fault shown on YouTube, shows the Duo Valve on both models being in the centre of the baulkhead, rather than under the Master Cylinder!
if anybody has any information as to easily access this difficult location of the valve, I would really appreciate it!
Many Thanks to all.
Eddie
 
Equally likely to be a temp sensor. Best to get the fault codes read before going any further.
 

s-l500.jpg

looks to have push fit connectors [clips] MAY NEED A SPECIAL TOOL TO MAKE THINGS EASY?


SDS star diagnostic system [MB's system]

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looks to have push fit connectors [clips] MAY NEED A SPECIAL TOOL TO MAKE THINGS EASY?

I used a wire to release clips by wiggling hoo under clip and pulling clips 'half way'. Check new valve how they works and pull also new clips ready out before assembling, then you need just to push them back in.

Done that in my W211 and C219 both. Not a fun job but doable when it is not under brake master cylinder.
 

s-l500.jpg

looks to have push fit connectors [clips] MAY NEED A SPECIAL TOOL TO MAKE THINGS EASY?


SDS star diagnostic system [MB's system]

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.
Many thanks for that info! I have in my procession that same part, but having not removed the old unit because of it’s awkward location, it looks very different from the one shown on You Tube!
At least I know what SDS means now, but would still like to know if this part under the master cylinder is easily accessible if put up on a ramp ??
 
I suspect that access from underneath is as problematic as from above. I hate these spring hose clips [ theres only one in the video] they can often be replaced by a jubilee clip if there is access. For removal it may be easier to leave the hoses attached to the valve initially and disconnect them from the bulkhead end and only remove once the valve is out after noting their orientation. where did you get the part no from? post up your vin no here to check its correct
 
I suspect that access from underneath is as problematic as from above. I hate these spring hose clips [ theres only one in the video] they can often be replaced by a jubilee clip if there is access. For removal it may be easier to leave the hoses attached to the valve initially and disconnect them from the bulkhead end and only remove once the valve is out after noting their orientation. where did you get the part no from? post up your vin no here to check its correct
Hi. Vin No. for my vehicle is WDB2110262A331100 !
Many Thanks for your help!
Eddie
 
Hi Everybody. I have come across a Dilemma with my Duo Valve problem, in that I decided to get the problem sorted in a garage!
unbelievable variation in prices which varied from £115. All in, inc Vat. From an Indy, to £432. From a Merc main dealer!
I have booked it in with the Indy, but they cannot do it for another ten days!
My Problem is that one of the members has suggested giving the valve a wack, of which I have tried, and strangely the heater is now blowing hot again !🤨
Do I cancel the repair, or has anybody experienced that the problem will return ?
Many Thanks in anticipation of a reply!
Eddie H.
 
Hi Everybody. I have come across a Dilemma with my Duo Valve problem, in that I decided to get the problem sorted in a garage!
unbelievable variation in prices which varied from £115. All in, inc Vat. From an Indy, to £432. From a Merc main dealer!
I have booked it in with the Indy, but they cannot do it for another ten days!
My Problem is that one of the members has suggested giving the valve a wack, of which I have tried, and strangely the heater is now blowing hot again !🤨
Do I cancel the repair, or has anybody experienced that the problem will return ?
Many Thanks in anticipation of a reply!
Eddie H.
I would go ahead and have the work done at the indy in 10 days time. There is a good chance the fault will return.
I wouldn't want to be without heating when the really cold weather sets in.
 
As above. Get it done; it will fail again. It is a very simple tiny (cheap?) motor and valve assembly inside and it is clearly not operating as smoothly as it should be. Mine failed then started working again of its own accord - but still changed it before it failed again. If you don't change it you can pretty much guarantee that it will fail on a freezing day and £115 will look very cheap.
I think the variation in price is that the official procedure is to remove the brake servo (on the non SBC cars anyway) which adds time - but some techs (with small flexible hands) have worked out how to do it by feel without removing the brake servo - hence able to do it quickly and more cheaply.
 
I would go ahead and have the work done at the indy in 10 days time. There is a good chance the fault will return.
I wouldn't want to be without heating when the really cold weather sets in.
Many thanks Mr. Geed, I couldn’t believe the difference in quotes between Indy, and Main Dealer !
As above. Get it done; it will fail again. It is a very simple tiny (cheap?) motor and valve assembly inside and it is clearly not operating as smoothly as it should be. Mine failed then started working again of its own accord - but still changed it before it failed again. If you don't change it you can pretty much guarantee that it will fail on a freezing day and £115 will look very cheap.
I think the variation in price is that the official procedure is to remove the brake servo (on the non SBC cars anyway) which adds time - but some techs (with small flexible hands) have worked out how to do it by feel without removing the brake servo - hence able to do it quickly and more cheaply.
Many Thanks for your reply! Your comment makes complete sense!
Thankyou Eddie.
 

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