E200 Heater Stuck on Hot ?

[LeeAshcroft]

Hi,

I bought an E200 two days ago and the heater is constantly stuck on Hot. Any idea what is causing this or how to fix it ?

 

[neilrr]

If the heat is on constantly REGARDLESS of where the controls are chance are the duo valve is to blame.

If the controls are frozen in position I'd take them out, fiddle around with them & see if they come free.

 

[LeeAshcroft]

Thanks for the reply. The heater is constantly blowing out hot air no matter where the controls are set.

Somthing else to note is that no matter how high you put the fan, you can hear the fan getting faster but only a trickle of air come out.

Is this a hard bit to replace ? Do you know where i could source one from or how to test if it definitely is this ?

 

[neilrr]

If it's a W210 you can see what's up here http://www.mbclub.co.uk/forums/engine/26854-howto-clean-duovalve.html

Roughly the same location for W124s. New, these are expensive. Used on ebay or from a breaker's yard they are cheap-ish.

Easy to replace as everything is accessible.

 

[LeeAshcroft]

Thanks. If i can't get it to work is there any way to make it so that it always blows cold air instead of always blowing hot air until i can afford a new valve ?

 

[neilrr]

I think the default setting is "roast" when the thing goes on the blink.

EDIT: Just noticed the year. Do you know the part number of your duo valve?

 

[LeeAshcroft]

Afraid not, do you know where i can find this ?

 

[neilrr]

An MB dealer can tell you from the VIN.

 

[LeeAshcroft]

Is it possible to force the pins to stay into a closed (cold) position or by reversing the cable supplying the voltage to the electromagent ?

 

[LeeAshcroft]

Morning All

Took the Duo Valve out this morning and gave it a clean.

To test it i reconnected the voltage and moved the temperature knobs up and down and only one of them moved (previously none of them).

The one that doesnt move, probably the coil has a break in it. i've reversed the spring on the one that doesnt move so it's always in the cold position, at least i now get cold rather than 'Cooked alive' Looks like i'm going to need to buy a new one. Does anyone know a good supplier (and cheap!)?.




On another note, when the fan speed is turned to full, only a trickle of air comes out of the vents. Does anyone know why this is or how to fix it ?

I read somewhere it may be the pollen filter being clogged up. I had a look for it this morning but couldnt locate it in the engine. The car hasnt been services for 55,000 miles so it is possible !

I'm not sure if it's relevent, but when i press the recirculate air button, the airflow doesnt increase any more. Does it still go through the pollen filter when it's recirculating?

Can anyone point me to where this is in the car or if there could be anything else causing the slow airflow ?