Help needed, no heat S320 cdi 02 REG

[patrick]

Hello guys some help needed
I can`t get any heat in the car, I have set the climate control to 23 degrees and above, all I get in return is the middle vents not blowing at all and the side vents blowing cold air even after 50mile trip, any help would be welcome.

 

[franey]

Thermostat?
I have the same car and had to replace it early this year.

 

[patrick]

thanks for reply franey, any idea as to how I can check, replace the thermostat?

 

[franey]

Replacement is quite straight forward, is yours the 613 or 646 engine?
Pre face lift or facelift?

 

[patrick]

pre facelift

 

[Lugy]

I'd suggest it was either the in car temperature sensor-I'd test the resistance when cold then use a hair drier maybe to check it's sensing the heat (I've no idea where it is though) or the temperature mixing flap-in my Saab it was right in the bowels of the dash.

 

[franey]

Should be this one:

Mercedes Thermostat 6112000515 Cdi Engines on eBay (end time 09-Oct-09 22:57:05 BST)

...........and yes its me selling it!!

Free postage though if you find you need one.

 

[tromppost]

you may have to get the fault cleared after the part is changed!

 

[patrick]

is this a diy job or do i have to take it in to get it done? also it is not showing any fault in the display, if i change it will the fault message then come up? @ franey my ebay name is nnaibe, will buy it so pls send me an invoice with ur free postage offer. thanks

 

[proser]

It's a DIY job, done mine earlier this year - takes no more than an hour.

 

[Lugy]

When you mean no heat do you mean the temperature gauge stays low when driven, but still will rise when stationary? Or are you meaning you can't get any heat in the car through the heater?

IME first option is the the thermostat, second is what I mentioned above

 

[Diesel Benz]

When you mean no heat do you mean the temperature gauge stays low when driven, but still will rise when stationary? Or are you meaning you can't get any heat in the car through the heater?

IME first option is the the thermostat, second is what I mentioned above

Thermostats have issues on the W211, making the engine run too cold. As you say, it would be important to know how the engine temperature gauge behaves.

Does the 220 have any issues with the hot water circulation control (I'm not familiar with this model, older ones had issues with the mono/duo valves and the 211 has had issues with the heat exchanger shuttoff motor)?

 

[AndyPCD]

I would go for the thermostat as i have done a few of these now for the same problem. The gauge reads ok because the engine temp is getting to the right temp but the thermostat is not opening to allow the coolant to flow to the heater matrix.
They are really easy to do and as said above should only take about and hour to do including bleeding up the cooling system.
You will not have to get the faults cleared as it is mechnical and will not store a fault as the cooling system in the eyes of the engine ecu is working correctly.

But if you dont feel like doing it or run into problems im about 20 inutes from you so am willing to lend a hand

 

[patrick]

UPDATE: I have changed the thermostat but still dont have any hot air coming out of the vents.(still as cold as before). the engine temp reads as normal (ie when driving, engine temp rises to correspond with driving style traffic, length of drive.) Any more advice will be greatly welcome.

 

[AndyPCD]

One other thing it could be is the duo valve which controls the flow of coolant to the heater matrix and if this stuck shut it will not allow and coolant flow into the matrix thus not heating up and allowing hot air to blow out.

These are not a very nice job to do

 

[BlackC55]

+1 . Tricky one that.

 

[patrick]

thanks for getting back to me. Any idea where the duo valve is ?

 

[AndyPCD]

Its under the wiper mechanism so that all has to be stripped out and even then its a bit difficult to get to.

 

[patrick]

Problem solved, it was the duo valve, this has been changed and heating is now working. Thanks guys

 

[AndyPCD]

Glad you got it sorted